The Mother Lode region of California

storms, William H

The Mother Lode
region of California

PASC

Af23

I

i

n

The May Rock, Mariposa County.

Ckoi'pings of the Eagle-Shawmut Mine, Tuolumne County.

L

xlLIFORNIA STATE MINING BUREAU.

A. S. COOPER, State Mineralogist.

BULLETIN No. 18.

San Francisco, October, 1900.

TH E

'^ ther Lode Region of California,

By W. H. STORMS, E.M.

f ublished under the Direction of HENRY T. GAGE, Governor of the State of California.

SACRAMENTO:

A J. JOHNSTON, : : : : superintendent state printing.

1900.

CONTENTS.

LETTER OF TRANSMITTAL ------- 3

INTRODUCTORY - . . - 5- 6

GENERAL GEOLOGY OF THE GOLD BELT - - . - 7- u

The Schists and Metamorphic Rocks - - - - -8-13

The Alteration of Other Massive Rooks - - . - 13- 14

SEVERAL DIVISIONS OF THE GOLD BELT - - - - -14-26

The Central Gold Belt ------- 15- 16

Classification and Description of Rocks ----- I6- 18

The Dolomitic Vein -------- 19- 21

The East Lode - 21-26

METHODS OF MINING - - 26- 35

Timbering - - - - - - - - - -29-31

Filling - - 31-32

Drainage - - - - - - - - - -32-33

Comparison of Steam and Cornish Pumps - . - - 33- 35

The Diamond Drill .--.-.-- 35

THE COST OF MINING - 3&- 39

Detailed Cost of Mining at Mahoney Mine - - . - 36

Detailed Cost of Milling at Mahoney Mill - - . 37

Detailed Cost of Mining and Milling at Gwin Mine - - 38

MINING MACHINERY 39-40

MINE BELL SIGNALS - - - - - - - -40-42

California Code of Signals -..--. 40- 42

THE MINES OF AMADOR COUNTY - - - - - -43-87

THE MINES OF EL DORADO COUNTY 88-89

THE MINES OF CALAVERAS COUNTY - 100-127

THE MINES OF TUOLUMNE COUNTY ----- 128-141

THE MINES OF MARIPOSA COUNTY 142-147

THE MINES OF MADERA COUNTY ------ 148-150

LIST OF ILLUSTRATIONS.

Fig. Page.

1. Diagrams illustrating the transition from jointing to schistose structure in

Greenstones ---------- lo

2. Method of working veins in swelling ground - - - - - 29

3. Separator at the Zeila slimes plant - - - - - - 47

4. Zeila canvas plant, Jackson -..---.- 48

5. Canvas table, Zeila Mill ..-.---- 48
(). Hydraulic ejector at Zeila slimes plant - - - - - - 49

7. Pointed box at Zeila slimes plant ------- 50

8. Plan of Groom distributor -------- 51

9. Manner of placing machine-drill holes, Kennedy shaft _ _ - 54

10. Sketch showing strike of formation at Kennedy shaft - - - - 55

11. Horizontal section showing timbers in Kennedy vertical shaft - ■ - 56

12. Vertical section showing method of timbering of Kennedy shaft - - 57

13. Vertical geological section of Argonaut-Kennedy vein - - . 59

14. Sketch showing strike of formation at new Oneida shaft - - - - 60

15. Station at 1900-foot level of Oneida Mine ----- g1

16. Station at 2000-foot level of Oneida Mine ------ 62

17. Geological sketch, Wildman Mine ------- 65

18. Fault, 900-foot level of the Mahoney Mine ------ 66

19. Sketch of vein in Wildman Mine ------- 67

20. Slaty cleavage in folded strata at Sutter Creek - - - - - 67

21. Sketch showing strike of formation at vertical shaft, Wildman Mine - 68

22. Section of guides and divider in Wildman shaft - - - - - 69

23. Method of timbering in Wildman shaft ------ 69

24. Screen frame, Wildman Mill --------70

25. Old style of screen frame at Wildman Mill . - . - - 71

26. Cross-section of Lincoln Mine, Sutter Creek - - - - - 73

27. Corrugated chuck-block, Keystone Mill ------ 79

28. Method of timbering, Gwin Mine - - - - - - - 101

29. Screen frame and chuck-block at Gwin Mill ----- 103

30. Geological section of Sheep Ranch Mine ------ 105

31. Geological cross-section near San Andreas, Calaveras County - - 106

32. Mill screen, Lightner Mill, Angels - - - - - - - 110

33. Chuck-block, Lightner Mill -------- 110

34. Chlorination vat, Utica Reduction Works, Angels ----- no

35. Fault in Pine Tree Mine, Mariposa County ----- 143

36. Cross-section Rex Mine, Madera County - - - - - - 148

37. Horizontal section. Rex Mine, Madera County - - - - 149

May Rock, Mariposa County ...--. Frontispiece

Croppings of the Eagle-Shawmut Mine, Tuolumne County - - Frontispiece

Oneida Mine, Amador County -------- 61

Central Eureka Mine, Amador County - . - . - . 61

Mahoney Mine, Amador County -------- 65

Timbering in caving ground, Mahoney Mine, Amador County - - - 65

Lincoln Mine, Amador County -------- 73

Bunker Hill Mine, Amador County ------- 73

North shaft and mill, Utica Mine, Calaveras County - - - - - 113

Keystone Mine and Mill, Amador County ------ 113

Croppings of tlie Mariposa Vein, Mariposa County - - - - - 145

Croppings of the Louisa Mine, Mariposa County ----- 145

LETTER OF TRANSMITTAL.

San Francisco, Cal., September 30, 1900.
To His Excellency Henry T, Gage, Governor of the State of California;
The Honorable The Board of Trustees of the California
State Mining Bureau; and Hon. A. S. Cooper, State Mineralogist.

Gentlemen: I have the honor to submit herewith the report of my
investigation of the mines of the Gold Belt in El Dorado, Amador,
Calaveras, Tuolumne, and Mariposa Counties during the spring and
summer of 1900. I regret that the necessity of visiting some of the
northern counties of the State during June and July made it impossible
to complete the work during the season, but, as it is a field of active
operation, the coming year will find development further advanced, and
at that time the investigation may be continued with more satisfactory
results than would have been obtained had the work been done the past
season. Very few other than operating mines were visited, and of these
the description in this bulletin is limited to the most important ones,
the others appearing in a general report which shortly follows this
bulletin.

I find among the more progressive superintendents and mine managers
a disposition to experiment with a view to improving mining methods
and to decreasing the expense of treating ore, and as a result we find
not a few innovations which in most cases will be adopted in general
practice, with such further improvements as additional experience may
suggest.

It affords me great pleasure to state that the mine owners, managers,

and superintendents, almost without exception, spared neither time nor

trouble in affording every facility for investigation of the mines under

their direction, which made the task not only light, but pleasant.

I am, yours respectfully,

W. H. STORMS.

THE MOTHER LODE REGION OF CALIFORXIA.

By W. H. STOEMS, E.M.

The California Gold Belt has furnished a most interesting field for
geological research ever since its discovery in 1849. It has received the
attention of many geologists, and a great deal has already been pub-
lished concerning it. Among the most noted and valuable of these con-
tributions to our knowledge of the Gold Belt are the early writings of
Dr. Rossiter W. Raymond and Ross E. Browne, and more recently those
of H. W. Fairbanks and Ross Browne, and the exhaustive maps and
reports of the United States Geological Survey. The various reports of
the State Mining Bureau have also furnished a large amount of valuable
technical and statistical information on the subject.

In consideration of the very large amount of descriptive matter
already published concerning the mines of the Gold Belt, or Mother
Lode, it was with the feeling that the subject was worn somewhat thread-
bare that the writer undertook the re-investigation of this important
mining field in January, 1900.

Since the publication of the Xlllth report of the State Mineralogist
in 1896, no publication has been issued by the State regarding the
progress of work in the counties along the Gold Belt, though this period
has been one of unusual activity and progress and also of innovation in
these mines. Old methods have in many cases given place to more
modern ideas, and still more radical changes may be anticipated in the
near future.

An era of deep mining has commenced which can only be carried to
the greatest success by the adoption of modern mining methods and
improved machinery, together with a closer attention to the economical
treatment of the ores. Already it has been shown that mines which
were worked in former years under disadvantages and at an expense
considerably above that now necessary to accomplish given results,
after years of idleness, upon being reopened and equipped with modern
machinery, can again be made to yield a handsome profit, where
formerly some of them were worked at a loss.

This has been made possible by the reduced cost of labor in later
years; by the superior efficiency of nitro powders over the black blast-

6 CALIFORNIA STATE MINING BUREAU.

ing powders used formerly in all mining operations in this State; by
better and cheaper mining supplies of all kinds; and in no small
degree, by improved hoisting, pumping, and milling machinery, and to
some extent also by improved mining methods.

There is little doubt that the marked mechanical success attending
very deep mining elsewhere, notably in the Lake Superior copper mines
and in the gold mines of South Africa, has proven a great incentive to
the miners of California to emulate, in a measure at least, these splen-
did efforts, and we now find large vertical shafts being sunk to a depth
far exceeding anything heretofore attempted in California mines.

There are mines in Amador and Nevada Counties now operating to a
depth of 2500 feet or more through old inclined shafts, usually sunk to
conform to the dip of the vein, or approximating it, and there are numer-
ous mines in several mining counties where inclined shafts are down
1500 to 2000 feet. The managers of these properties realize the impor-
tance of having shafts sunk at a uniform angle — whether vertical or
inclined — thoroughly equipped and provided with the best hoisting
machinery in order to reduce the cost of mining to a minimum, for in
nearly all of the large mines it is known that there are immense bodies
of low-grade ore, too poor to pay when worked by old methods, but which
would afford a good profit if mined by mojdern methods and with well-
equipped shafts and machinery of proper construction. This matter
will be more fully discussed under the title of " Methods of Mining."

The introduction of extensive slimes plants, and the successful opera-
tion of the cyanide process in its various forms, have also contributed
in a measure to increased financial success, and electric plants have
also been installed at several points for the distribution of power to
mines along the Gold Belt. These installations are said to be success-
ful financially as well as mechanically. Transmission of power through
the medium of compressed air, though not an innovation, is more exten-
sively employed than formerly.

THE MOTHER LODE REGION — GENERAL GEOLOGY.

GENERAL GEOLOGY OF THE GOLD BELT.

Owing to the extremely complicated structural geology of the Cali-
fornia Gold Belt, positive assertions as to the relative age of the intru-
sive rocks which so commonly occur throughout its length are generally
unsafe, but in a general way it may be stated that, upon rocks of an
uncertain but very great age, possibly Archasan, there was laid down in
Palaeozoic time a deep series of sediments consisting of mud, sand,
finely comminuted calcareous fragments, calcareous ooze, etc. Follow-
ing this there was evidently a long period of volcanic activity, during
which there was accumulated a vast quantity of basic rocks, chiefly
diorite and diabase, and basic tuffs and breccias. These rocks are
mineralogically closely allied to the andesites, and are called the old
andesites by the United States Geological Survey. The underlying
formations, together with the tuffs, were consolidated into rock; the
mud being transformed into shale, and by further process of meta-
morphism, into slate, the sand becoming quartzite, and the calcareous
material, limestone.

There were evidently successive periods of elevation and subsidence
also, resulting in the formation of extensive beds of conglomerate along
the shore lines. During the Jurassic age there was deposited upon these
older formations a stratum of fragmentary material consisting of fine
silt and sand, forming eventually thick beds of shale and sandstone.

During a portion of this period volcanic activity was again pro-
nounced, particularly about the close of the period, during which there
was again accumulated a large amount of diabase tuffs and breccias.
In some localities the mud deposits and the tuffs are found interbedded,
showing that the volcanic outbursts were intermittent. In some cases
a sandstone is found wholly made up of diabase material, and this is
probably the result of the disintegration of some previously erupted
material, which was carried down from an elevated ridge and deposited
in the bed of the sea. These sediments have subsequently been uplifted,
folded, crushed, and faulted. The dynamic forces were still at work,
and large dike-like masses of diabase, diorite, serpentine, and other
intrusive rocks were thrust from below into the complex of older rocks.

The Palaeozoic rocks, owing to their large development in Calaveras
County, have been named the Calaveras formation, and the later deposits
of Jurassic age have been called the Mariposa beds (as this formation
is most extensively exposed in Mariposa County), and it is in more or
less close association with these beds that the so-called Mother Lode of
California occurs.

Lying to the eastward of the above described formations is found a
broad expanse of intrusive rock, which, owing to its peculiar mineral-

O CALIFORNIA STATE MINING BUREAU.

ogical character, has been named grano-diorite. At numerous points
along the contact of the grano-diorite with the formations heretofore
mentioned there is found abundant evidence that the grano-diorite was
intruded later than the greenstones, and it is also later than the Mari-
posa beds. There is some reason to believe that the grano-diorite is as
late as the Cretaceous.

The Mariposa beds appear generally to occupy a position along the
trough of a synclinal fold, the Calaveras formation being found both to
the eastward and westward of the Mariposa beds. The occurrence of
the diabase tuffs and the intrusion of great masses of basic dike rock
(diabase and diorite) have rendered the positions of the Mariposa beds
and the Calaveras formation very irregular and often extremely puz-
zling, as the distribution of the tuffs, breccias, and intruded dikes is
most erratic. It is more than probable that a cross-section taken every
half, or even every quarter mile along the Gold Belt, would show an
entirely different structural condition.

The Schists and Metamorphic Rocks. — The tremendous compressive
stress to which these rocks have been subjected since their uplift, has
resulted in the formation of a series of highly crystalline metamorphic
rocks — the mud being altered into slates, the sandstones changed to
quartzite, and not infrequently the limestones are found altered to
marble. The greenstones have likewise been changed over broad areas.
The pressure and movement accompanying it have resulted in many
cases in a complete obliteration of the original character of the normal
rocks, and in place of the crystalline granular greenstones we find
schists and slates (the amphibolite schist of the United States Geolog-
ical Survey). Throughout the entire length of the Gold Belt are found
greenstones of greatly varying texture (chiefly diabase), which have
suffered little or no alteration.

These masses of greenstone are from a few feet to several hundred
feet in width, and it seems not improbable that they were mostly intru-
ded since the formation of the schists. In some instances this is posi-
tively known to be the case, as they are found cutting the schists in
strike and dip. In some of the gold mines these greenstone dikes may
also be clearly seen to be more recent than the inclosing rocks, and
occasionally they are found intersecting the quartz veins.

Instances may be observed, however, where only portions of certain
massive formations are schistose, and this can only be attributed to the
local effect of the dynamic forces similar in character to those which
produced the original metamorphism of the older formations. The gen-
eral features of the schistose greenstones (both massive and tufaceous)
occurring in California are so similar physically to those of the Mar-
quette and Menominee regions of Michigan that there seems no room to

THE MOTHER LODE REGION — GENERAL GEOLOGY. 9

doubt that in each case similar causes operated to produce like effects.
The Michigan region has been studied with great care by several of the
best geologists of America. Those interesting rocks and the manner of
their formation have been fully described by G. H. Williams, and a few
extracts are taken from his excellent contribution to this important
subject, the dynamic metamorphism of eruptive rocks,* for the reason
that they apply so perfectly to the conditions found in California along
the Gold Belt, and I have not the slightest doubt that greenstone schists,
wherever found, whether as the result of the alteration of massive green-
stone tuffs or of fragmental rocks (sandstones), derived from the degra-
dation of older greenstones, are the direct result of the causes ascribed
by Mr. Williams as having produced the schists of the Michigan region.
In referring to the value of the microscope in the study of metamor-
phism of rocks, Mr. Williams says:

The most important problems presented by an unaltered massive or igneous rock
relate to (1) its chemical composition, and (2) to the conditions under which it was
formed. The composition expresses itself in a general way, in the nature of the com-
ponent minerals, while physical conditions attendant upon the formation of the rock
may be traced in its structure. Each of these has therefore been, in turn, the particular
object aimed at during the first two periods of petrographical research.

But if petrography were able to solve satisfactorily all the problems presented by the
unaltered massive rocks, it would even then be prepared only to commence its most
difficult and most important mission. Rocks are in reality far from being dead, inert,
stationary masses, which they appear to the ordinary observer. The fascinating study
of chemical geology, especially when aided by the microscope, shows them to be in a
state of almost constant change. It is true that some of the oldest rocks seem to have
suffered hardly any alteration since they were first formed, but most of them are ever-
active laboratories where old products are being pulled to pieces and new ones built up.
The tracing-out of such changes is an important aim of petrography in its present stage.

In the study of the structural geology of the California Gold Belt, it
was found necessary to employ the microscope, and the conclusions
reached in this study are identical with those submitted by Mr. Williams.
Upon his study in the Michigan area, continuing, he says:

There are two distinct kinds of alterations which take place in a solid rock mass,
dependent, of course, on the nature of the changed physical conditions. These are:

(1) Metamorphism ; or the passage, under circumstances of high temperature or
pressure, or both, of less crystalline into more crystalline compounds ; or the change of
minerals into others not less crystalline or insoluble than themselves.

(2) Decomposition or weathering ; the passage, under ordinary atmospheric condi-
tions, of crystalline rock constituents into compounds less crystalline and more soluble
than themselves. This is accomplished generally by hydration or carbonization.

Both of these processes are frequently seen to have gone on in succession in the same
rock mass, the latter more or less completely effacing the effects of the former. While
distinct, both processes agree in being atomic and molecular rearrangements in a solid
mass, necessitated by some change in external conditions. The differences in these
conditions, however, produce widely different results; and all of these again are
essentially different from those produced by the solidification of a liquid magma,

.The student of the crystalline rocks can distinguish, in a general way, four classes of

* Bulletin No. 62, United States Geological Survey. "The Greenstone Schist area of the
Menominee and Marquette regions of Michigan."

10

CALIFORNIA STATE MINING BUREAU.

constituent minerals, and this is true in spite of the fact that the same species may be
represented in two or more of these classes :

(1) Original minerals of the acid rocks, formed by the solidification of a magma in
a state of aqueo-igneous fusion or by the aid of mineralizers ; e. g., quartz, orthoclase,
mica, zircon, etc.

DiAG»F\AN)s 'illusi:rati't9§-Moe-rrahsi-i"ioi9 fron^ jointing
fo schistose sti'uc-l'u res in the oreens-fones.

Fig. 1.

(2) Original minerals of the basic rocks, formed from a state of dry fusion ; e. g.,
plagioclase, augite, olivine, etc.

(3) Metamorphic minerals, formed as above exi)lained, from originals; e. g., horn-
blende, albite, biotite, zoisite, garnet, staurolite, andalusite, etc.

(4) Decomposition minerals; e. g., chlorite, quartz, carbonates, hydroxides, etc. * *

I

THE MOTHER LODE REGION — GENERAL GEOLOGY. 11

Rocks may be altered by simple pressure, but the accumulated strains which are
L'liierated within them are relieved and adjusted by overcoming the force of cohesion
along certain planes. Here there will be a shearing motion of greater or less extent,
and a consequent crushing of the rock. The rent is soon healed by the crystallization
of new compounds which cement the crushed fragments, and in this way a schistose
band, of width varying with the intensity of the force, may be developed in the midst
of an otherwise solid and massive rock ; or a number of such bands may be formed
parallel to one another and together imparting to the rock the appearance of a foliated
or even a banded schist.

Conclusive proof of this process might be diflQcult to discover without the aid of a
microscope, but this instrument is happily able to afford sufficient evidence to overcome
all doubt. * * *

The first step toward the formation of a schistose structure in Twin Falls green-
stones (and this is hardly ever absent) is tlie division of the massive rock by two
systems of joints, which stand about perpendicular to the surface and intersect at a
varying but acute angle. These joint systems divide the mass into diamond-shaped or
rhomboidal prisms, the cross-sections of which are well displayed upon the frequent
smoothly glaciated surfaces of the rock. The appearance of such a surface is diagram-
matically represented in Fig. 1.

As we approach the schistose band in the massive rock these interlacing rhombs
become lengthened out more and more by an approximation to parallelism between
the two systems of joint planes.

These elongated prisms finally become very much extended lenses, which interlock
and produce a well-developed, wavy, or even parallel schistose structure. The almost
slaty rocks thus produced, especially as seen at Lower Twin Falls, have a tendency to
break, not so much along a definite plane, as parallel to a line— i. e., the direction,
normal to the surface, parallel to which the original joint planes ran. It is difficult to
obtain well-shaped hand-specimens of these rocks, but narrow rhombic prisms of
almost any angle are easily procured. There is an almost equal tendency to cleave
along any plane which is yjaraliel to the longest axis of these prisms.

If the prisms due to the original joint planes were subjected to a lateral pressure
which developed in them a cleavage that successively approached more and more nearly
to the long axis as the prism was lengthened, this peculiar tendency to separate along
a line rather than along a plane is preciselj' the structure which we might suppose
would result.

The strike of these schistose bands follows the direction which bisects the acute
angle of the rhombic prisms. This is for the most part from S. 70° to 80° E. ; agreeing
with the prevailing strike of all the rocks in this system. There are, however, many
exceptions where these schistose bands, even where near together, follow different
directions ; for instance, I observed in the massive though jointed rock on the Michigan
side of Upper Twin Falls, two schistose chloritic bands quite near together, one having
a strike N. 180° E., and the other S. 73° E., while the dip of each was nearly vertical.
Such cases are easily explicable on the supposition that these bands were produced by
mechanical agencies, but it is quite impossible to reconcile them with the supposition
that these bands are in any way the result of sedimentation.

It is not infrequently noticed that there is a local development of
schistose structure of massive rocks in the immediate neighborhood of
fissures and veins. A typical instance of this character may be observed
on Wood's Creek, a few hundred feet below the pumping-station, near
the Bonanza Mine at Sonora, in Tuolumne County. Here a quartz
vein, about twelve inches in width, traverses a hard, dark-green diorite.
The walls on either side are altered for a width of three to five feet,
being soft talcose or chloritic schist near the vein, and passing over by
transition to the normal diorite. These occurrences are not at all
uncommon, though often of local character.

12 CALIFORNIA STATE MINING BUREAU.

In Amador and Calaveras Counties, and also to some extent in
El Dorado County, I found peculiar banded schists, whicii have attracted
the attention of many geologists. Similar banded schists occur in the
Michigan area, above referred to, of which Mr. Williams speaks as
follows:

The banded greenstone schists which form the prevailing rock over the northern por-
tion of the Marquette area, have been regarded by all geologists who have ever studied
them, as originallj'^ sedimentary deposits, and repeated examination of them in the field
seems incapable of leading to any other conclusion. They are everywhere stratified
with the greatest regularity in bands of lighter and darker shades of green. This
structure is to be most advantageously seen in the woods just north of Marquette and
near Lighthouse Point. Here glaciated areas of considerable extent often show a finely
ribboned appearance, looking as though the sharp parallel lines had been drawn with a
ruler. The alternation in the composition of the layers is so frequent and so constant)
and their jjarallelism to the east and west strike of all the rocks in this neighborhood is
so exact, that no hypothesis of their originally massive character will satisfactorily
account for the observed facts. * * *

On the other hand, their chemical as well as their mineralogical composition renders
it impossible to separate them from the massive and highly altered greenstones (uralite
diabases, etc.), with whicli they are most intimately associated. Their parallel banding
indicates a fragmental, but their chemical and their mineral composition indicate an
igneous, origin. The only satisfactory reconciliation of these opposite sets of characters
is to be found in that group of rocks intermediate between sediments and lavas,
known as volcanic tuffs.

In the op)inion of the writer, then, the banded greenstone schists of the northern Mar-
quette area are to be regarded as consolidated and highly metamorphosed diabase tuffs.
These are intimately associated with the numerous contemporaneous flows of diabase
and quartz porphyry, together with the tuffs of the latter rock ; while all have been
broken through by much younger dikes, both basic and acidic.

************
In order to obtain a clear idea of just how these ancient and miuch disguised tuffs
acquired their present form and apparently dual character, it will be advantageous to
ascertain what is known of analogous formations of comparatively recent date. Captain
C. E. Button's descriptions of the fragmental rocks accompanying the Tertiary erupt-
ives of the high plateaus of Utah are well suited to this purpose. He says, in speaking
of the extent of these deposits :

" Some of the most interesting lithological problems presented by the volcanic products
of the high plateaus are those relating to the origin and development of what may be
termed the clastic igneous rocks, or rocks apparently composed of fragmental materials
of igneous or volcanic origin, but now stratified either as so-called tufaceous deposits or
as conglomerates. These are exceedingly abundant in all of the great volcanic districts
of the world, and often enormously voluminous.

" How those of the high jilateaus would compare, in respect to magnitude, with those
of other regions, I do not accurately know, but absolutely their bulk is a source of utter
astonishment. They cover nearly 2000 square miles of area, and their thickness ranges
from a few hundred feet to nearly 2500 feet, the average being probably more than 1200
feet. Lavas are frequently intercalated, but much more frequently no intercalary lavas
are seen, and in general they seldom form any large proportion of the entire bulk when
they occur in conjunction with the clastic masses."

Again, in speaking of the peculiar liability of such deposits to metamorphism, tlie
same writer says:

" A very striking characteristic of these clastic volcanic rocks, both the tufas aii<l
the conglomei-ates", is their great susceptibility to metamorphism. Not only have the
beds in many localities been thoroughly consolidated, but they have undergone crystal-
lization. These tufas and conglomerates, wliich are of older date, and which have been
buried beneath more recent accumulations to considerable depths, rarely fail to show

THE MOTHER LODE REGION — GENERAL GEOLOGY. 13

riiispicuous traces of alteration, and in many cases have been so profoundly modified
that for a considerable time there was doubt as to their true character.

• The general tendency of this process is to convert the fragmental strata into rocks
having a petrographic facies and texture very closely resembling certain groups of igne-
ous rocks. When we examine the rocks in situ, no doubt can exist for a moment that
they are water-laid strata. The hand-specimens taken from the beds, which are
extremely metamorphosed, might readily pass, even with close inspection, for pieces of
massive eruptive rocks, were it not for the reason that the original fragments are still
distinguishable, partly by slight differences in color, partly by slight differences in the
degree of coarseness of texture. But the matrix has become very similar to the included
fragments, holding the same kinds of crystals, and under the microscope it shows a
ground-mass of the same texture and composition."

The Alteration of Other Massive Rocks. — The greenstones are not
the only massive rocks which have undergone a more or less complete
alteration in the region of the Gold Belt. There are two rocks in par-
ticular to which I wish to call attention. These are the calcareous
rocks which constitute the great dolomitic vein, previously referred to,
and a dark green, massive, extremely hard, and tough rock found at
numerous places along the Gold Belt, notably in Calaveras County just
east of San Andreas; near Dogtown, three miles from Angels; at
Smith's Flat, west of Angels, and elsewhere. The ankerite or dolomite
vein is usually distinguished by its great width and massive character,
and the occurrence of more or less abiSfidant mariposite; but in many
places we find this hard, thoroughly crystalline rock has been com-
pressed, sheared, and completely altered, passing over by gradual transi-
tion to typical soft talc schist.

A series of transition rocks of this character was obtained at the
Pacific Mine, Placerville, El Dorado County, and is on exhibition in the
Museum of the State Mining Bureau in San Francisco. Similar
occurrences have been noted in a score of mines, from Mariposa County
northward as far as Placerville, but collections from other mines have not
been placed upon exhibition, because the occurrence is essentially the
same in each case, and the space available in the Mining Bureau is
already crowded.

Concerning the other massive rock, hand-specimens were selected
from the Ford Mine at San Andreas, also from a similar occurrence at
the Smyth Mine near Angels, and slides cut for microscopic study.
These prove the rock to consist of a matted aggregate of minute scales
of talc, with a little calcite and magnetite. The rock, although the
freshest obtainable, is very evidently not in its normal condition, but is
an igneous rock which has already undergone considerable change. It
may have been a gabbro or some allied eruptive rock, which, by a
process of compression and shearing previously described, is now found
changed into a typical massive crystalline granular or schistose
steatite (soapstone). Undoubtedly, the alteration of massive rocks to a
schistose or slaty condition is very much more common than is generally

14 CALIFORNIA STATE MINING BUREAU.

supposed, but unfortunately too little attention had been given in the
past to these phenomena.

It has been noticed in several instances where mine workings have
been extended into the steatite masses, that not infrequently the rock is
found to consist of a coarsely crystalline aggregate of semi-schistose,
calcareous and magnesian minerals and to greatly resemble the partly
altered ankerite and dolomite found along the Central Gold Belt.
Notable instances may be found in the Ford Mine at San Andreas in
Calaveras County, and at the Spanish Mine near Forest Hill in Placer
County. As these rocks approach so nearly the dolomite of the Central
Gold Belt, they may be considered as indicating the possible origin of
the dolomitic veins from basic eruptives.

THE SEVERAL DIVISIONS OF THE GOLD BELT.

Throughout the entire length of the great synclinal trough of the
Gold Belt are found the gold-bearing veins which constitute the so-called
Mother Lode. It seems unfortunate that the name was ever given
to this portion of the Gold Bel1^» as it conveys to the minds of those
unfamiliar with the geological structure and veins of the region, an
impression of a continuous, unbroken vein. That such a condition
does not exist is well known to those familiar with these mines.

There are through that portion of the State occupied by the counties
extending from Mariposa on the south to the southern portion of El
Dorado County on the north, at least four distinctly recognizable gold
belts : That which skirts the low foothills along the Great Central Val-
ley includes the copper deposits found at and near Green Mountain in
Mariposa County, and southward in Madera County, those at Copper-
opolis and at Campo Seco in Calaveras County, and at Ranlett in
Amador County, and also the gold mines of Salt Spring Valley in
Calaveras County. It may also be considered as embracing the gold
mines near Hornitos in Mariposa County, and those near lone in Ama-
dor County.

East of this a distance of 8 or 10 miles is found the most important
gold-l)earing belt of the State, which has received the name of "Mother
Lode." This, it seems to me, it would be well to designate as the Central
Lode of the Gold Belt. It must be understood and remembered in this
connection that the gold-bearing veins are nowhere absolutely continu-
ous and unbroken for a great distance, but that the so-called lode is
frequently interrupted by its absolute disappearance for considerable
distances.

Lying east of the Central Lode, in Mariposa County, a distance of
nearly 20 miles, and extending in a northwesterly direction, nearly

THE MOTHER LODE REGION — THE SEVERAL DIVISIONS. 15

parallel with the Central Lode, and passing through Tuolumne and
Calaveras Counties, is the third gold-bearing lode, which in Amador
County has approached to within 6 to 10 miles of the Central Lode.
This is known as the East Lode, and embraces many interesting and
important mines.

Still farther eastward lies at least one mineral belt w^hich has been
opened at several points, but of which comparatively little is known as
yet. This might properly be named the Sierra Lode.

It is the intention to fully investigate this important field in the
future, as it is one of great promise. The veins are large, and carry
sulphides of iron, lead, zinc, and copper, and also gold and silver.

The Central Gold Belt. — It is with the Central Gold Belt we have
chiefly to deal in this Bulletin, as lack of time precluded a thorough
investigation the past season of the entire region comprising the Gold
Belt.

For years, in fact since its early history, the clay slates of the Mari-
posa beds have been considered an absolutely essential feature and
accompaniment of the important gold mines of the Central Gold Belt.
The veins have been referred to as "contact veins," and in many sec-
tions the immediate contact, or close proximity, of the Mariposa clay
slates has been deemed indispensable to pay rock.

Such, however, is apparently not the case in Amador County, where
are situated the deepest and most productive mines. While it is possi-
ble that some of these mines are confined wholly to the Mariposa clay
slates, or occur at contact of the Mariposa clay slates and massive
greenstones, or the amphibolite schists resulting from their alteration,
if such be the case the instance is unknown to the writer, for without
exception, the large number of accessible mines prove that the Mariposa
clay slates form really no important feature as related to ore deposition,
while thus far in Amador County, south of Plymouth, all development
confined to the typical clay slates of the Mariposa beds has proven the
fissures in that formation valueless, and these developments reach
many thousands of feet of shafts and drifts.

The fissures in which the ore deposits occur along the Central Lode,
with no exception, so far as the writer is aware, cut the dip and usually,
also, the strike of the inclosing rocks. The dip of the slatj' and
schistose formations is uniformly to the eastward, though at greatly
varying angles, but usually between 50 and 80 degrees, while the dip of
the vein fissures is always somewhat less in approximately the same
direction.

In the mines of Amador County are found a peculiar black slaty
rock, often approaching closely in physical appearance the clay slates of
the Mariposa beds. They may usually be readily distinguished by a
peculiar pitted appearance. This feature ranges from rather coarse.

16 CALIFORNIA STATE MINING BUREAU.

thickly scattered, knotty granules, to the fine dots resembling pin
pricks — the finer grained and the more slaty in structure the rock, the
finer are the pits.

For years these rocks have not been distinguished from the black
clay slates of the Mariposa beds, but the writer noticing that this
peculiar slaty rock was of persistent occurrence ^-ith the most impor-
tant ore-bodies of Amador County, determined to ascertain if possible
what, if any, difference there was between these pitted slates and the
smooth, satin-like slates of the Mariposa beds. With this object in
view, several series of rocks were collected at various mines, showing
complete transition from a massive or slightly schistose rock to a perfect
black slaty rock, the specimen always showing the pits as above
described, and being obtained from certain cross-cuts where the transi-
tion was evident.

These rocks were placed in the hands of H. W. Fairbanks, of Berke-
ley, who prepared slides and carefully studied them with the aid of the
petrographical microscope. This investigation resulted in proving that
these peculiar slates and schists were the result of the shearing and
alteration of tuffs (evidently diabase), and that the rock was originally
of fragmentary origin, though made up of diabase material (augite,
plagioclase, etc.). Their character is rendered perfectly evident under
the microscope, and the change from one phase of alteration to the next
may be clearly traced in the several rock sections.

CLASSIFICATION AND DESCRIPTION OF ROCKS
Collected toy W. H. Storms along Central Gold Belt.

Determinations made by H. W. Fairbanks, A.B.
Nos. 1 to 9, inclusive, From cross-cut 900-level, Keystone Mine, Amador County.

No. 10. From tunnel east of Keystone Mine, Amador County.

No. 11. From tunnel east of Keystone Mine, Amador County.

No. 12. From west wall of Oneida Mine, Amador County.

No. 13. From west wall of Oneida Mine, Amador County.

No. 14. From east shaft of Kennedy Mine, Jackson, Amador County.

No. 15. From east shaft of Kennedy Mine, Jackson, 900-level, Amador County.

No. 16. From hanging-wall of Bunker Hill Mine, Amador County.

No. 17. From Baliol Mine, Sutter Creek, Amador County.

No. 18. From west wall of xVrgonaut Mine, Amador County.

No. 19. From Carson Creek, Calaveras Coimty.

No. 20. From dike in Copperopolis Mine, Calaveras County.

No. 21. From dike in Commodore Mine, San Andreas, Calaveras County.

No. 22. From Ford Mine, San Andreas, Calaveras County.

No. 23. From Ford Mine, San Andreas, Calaveras County.

No. 24. From Smyth Mine, Angels, Calaveras County.

No. 25. From Smyth Mine, Angels, Calaveras County.

No. 26. From Pocahontas Mine, Logtown, El Dorado County.

No. 27. From German Mine, El Dorado County.

No. 28. From German Mine, El Dorado County.

No. 29. From German Mine, El Dorado County.

No. 30. From hill north of Church-Union Mine, El Dorado County.

No. 31. From hill north of Church-Union Mine, El Dorado County.

No. 32. From hill north of Church-Union INIine, El Dorado County.

No. 33. From hill nortli of Cliurch-Union Mine, El Dorado County.

THE MOTHER LODE REGION — THE SEVERAL DIVISIONS. 17

Nos. 1 to 9, inclusive, are from the 900-foot level of the Keystone. Some of these have
been su])posed to be dikes, but Mr. Storms is unable to tell from the section given where
the igneous rock ends and the supposed slate begins. A microscopic study of these
rocks shows that in all probability they are all of sedimentary origin, a series of tuffs
and slate, the tuffs being fragmental greenstones or diabases.

No. 1. This rock to the unaided eye has every appearance of being a dike. Porphy-
ritic crystals of augite are embedded in a tine green matrix. Under the microscope
this rock has the appearance of being a tuff. The constituents are badly decomposed
crystals of augite and cloudy masses of feldspar in a finely granular base. Granular
magnetite is present.

No. 2. To the eye this rock clearly betrays its tufaceous character. Its components
are arranged in irregular layers. Under the microscope the tufaceous character is also
seen. Augite crystals, granular magnetite, and cloudy tabular areas make up the rock.
A large part of the matter of the rock is indeterminable, but there is no doubt that it is
a diabase tuff.

No. 3. In the hand-specimen, this rock shows its clastic origin in the alternating
layers of greenish and argillaceous material. The green is probably tufaceous, and
the black of the same composition as the slates. Both show signs of metamorphism in
the presence of a pitted surface caused by little crystals. The exact nature of these
could not be determined, but in all these slates they are characteristic of metamorphic
action. Under the microscope this rock does not show clearly its origin. It might be
either a sedimentary rock or an altered igneous one. It is made up of ragged, clear,
and cloudy areas. A green mineral has the appearance of secondary hornblende.
There are some augite grains. This is a fine-grained rock.

Nos. 4, 5, 6, 7, 8, and 9. These are all black slate. In section they are practicallj'
opaque. In some there are little crystals with clear borders and dark centers, crystals
produced by metamorphism.

No. 10. This rock might be taken for a fine-grained eruptive greenstone, but under
the microscope it has much the appearance of being a fragmental greenstone. The
rock is much decomposed, but contains a large amount of augite and considerable
granular iron ore. It is somewhat schistose, the crystals and cloudy masses being
arranged along parallel lines. It is quite likely a fragmental rock.

No. 11. Also an augitic tuff. The rock mass is made up largely of augite crystals
thickly matted together with cloudy material and granular magnetite. The cloudy
material in these tuffs may have been originally the mud resulting from the grinding
up of diabase fragments.

No. 12. This is an augite porphj'rite, generally termed diabase or greenstone. The
rock is much decomposed ; shows prominent crystals of augite, but the feldspars have
almost completely disappeared in a greenish, cloudy mass.

No. 13. Diabase or augite porphyrite. This is a fresher rock than the last, but of
the same general character originally. It contains large crystals of augite, and smaller
ones of feldspar in a cloudy decomposed ground-mass. The rock is somewhat talcose.

No. 14. This is a medium-grained diabase. Under the microscope it appears to
consist largely of augite, with some small decomposed crystals of feldspar and iron ores.

No. 15. This is a fine-grained diabase tuff, and quite schistose. It is made up of
augite grains, and faintly polarizing masses are arranged in layers with opaque seams
between them.

No. 16. This is probably a greenstone tuff. It contains much cloudy matter, augite
crystals, others which were once feldspar, and some which resemble hypersthene. Mag-
netite scattered through the rock.

No. 17. This is a talcose schist derived from what was probably a fragmental green-
stone or tuff. The body of the rock is made up of thickly matted rods and scales of talc.

No. 18. Coarse diabase. This rock contains an excess of augite crystals fairly fresh
in character, and a cloudy base in which outlines of feldspar crystals can be made out.
It has been rendered schistose through pressure.

No. 19. Layers of augitic tuff and dark slate. Under the microscope the layers are
seen to be made up of cloudy indeterminable material, through which are scattered
fragments of augite crystals. They make up half of the rock. The dark bands contain
2— MB

J8 CALIFORNIA STATE MINING BUREAU.

less augitc and stringy opaque matter. They have the character of some of the slates
except for the scattered augite fragments.

No. 20. In tlie hand-specimen, Nos. 20 and 21 look much alike. The rocks are coarse
grained, with their dark constitutents altered to a green scaly talcose mineral. They
contain much feldsi)ar and cubes of iron pyrite. Under the microscope No. 20 is seen
to consist of an acid plagioclase feldspar, perhaps oligoclase, quartz, and a green
mineral replacing hornblende, also magnetite. This is a much decomposed rock, but
might be termed a quartz diorite.

No. 21. Under the microscope this rock is seen to consist of a decomposed feldspar
similar to No. 20, and green chloritic matter replacing some dark silicate, probably
hornblende. This rock is also a diorite.

No. 22. This is a massive green rock made up of an aggregate of fine talcose scales.
Under the microscope it appears very similar to No. 24, but shows no clue to its original
mineralogical constitution.

No. 23. This is a green rock, which in the hand-specimen is almost massive; made
up of an aggregate of fine lustrous scales. Under the microscope the rock is seen to
consist almost entirely of a matted aggregate of interlacing scales with the properties
of talc. There is also a little calcite and magnetite. This rock, then, is mainly a hydrous
silicate of magnesia, replacing some magnesia-rich igneous rock. The precise nature
of this rock cannot be told, for all traces of the original constituents have disappeared.

No. 24. This is a green talcose rock, showing dark gray and light green patches ; the
latter were probably once feldspar and the rock originally a gabbro. Under the micro-
scope it appears to be made up of an interlacing matte of talcose scales.

No. 25. This is a coarse rock, and to the unaided eye appears to be made up of feld-
spar and chloritic hornblende. Under the microscope it appears to be made of cloudy
feldspar, magnetite, and augite, partlj"^ altered to green hornblende. Might properly be
termed a diorite, although it was once a gabbro when in a fresh condition.

No. 26. This is a feldspar porphyry, with bronze-colored crystals of mica. Under
the microscope the feldspar is seen to be plagioclase. The rock may have contained
augite once. Strictly, it might be termed a diorite porphyrite.

No. 27. This rock is very similar to No. 28. It contains more augite, and is (juite
fresh.

No. 28. This is a grayish rock, with rather indistinct porphyritic crystals of feldspar.
Under the microscope it shows porphyritic crystals of augite and feldspar in a tine
granular ground-mass. This rock is very different from the greenstones. It is lighter
colored and fresher. It might be termed an augite porphyrite, although the feldspar
might make it an augite-diorite porphyrite.

No. 29. This is a hard gray rock, with rather indistinct crystals of white feldspar.
Under the microscope it appears to be badly decomposed, showing remnants of twined
feldspar crystals, magnetite, and a dark constituent entirely decomposed. Might be
termed a diorite porphyrite.

No. 30. This is a feldspar-quartz porphyry, showing large crystals of quartz, feldspar,
and a bronze-colored mica in a fine ground-mass. Under the microscope the quartz
appears much corroded, and the feldspars clouded. The ground-mass is made up of
a fine-grained aggregate of quartz and feldspar.

No. 31. This rock contains hornblende, quartz, and plagioclase feldspar crystals in
a granular ground-mass. In structure of components it lies between a granite and a
porphyry and might be termed a granite porphyry.

No. 32. This is a rather fine-grained greenstone or diabase schist. It consists under
the microscope of augite, pale green feldspar, probably labradorite, and iron ores. The
constitutents are much altered.

No. 33. This is a quartz-feldspar porphyry. It contains crystals of twined feldspar
(plagioclase), corroded quartz crystals, and a decomposed mineral possibly once horn-
blende. There may be some decomposed mica. Tliese constitutents lie in a fine
granular ground-mass.

H. W. FAIRBANKS, A.B.

THE MOTHER LODE REGION — THE SEVERAL DIVISIONS. 19

In every mine accessible along the Central Lode, from the Pocahontas
near Drytown on the north, to the Muldoon south of the Argonaut near
Jackson, where ore-bodies are found in contact with or in slaty rocks,
these slates are observed to be of the character described, and which the
microscopic study of Mr. Fairbanks proves to be the result of alteration
of tuffs, and not of massive diabase, as had been supposed by the writer.

The normal tuff is, however, massive, often fine-grained and containing
crystals of augite, and difficult to distinguish from crystalline green-
stone with the unaided eye; in this respect resembling the tufts of
Michigan, described by Mr. Williams, and those described by Captain
Button as occurring in the Great Basin region of Utah.

The clay slates of the Mariposa beds are found in cross-cuts extending
to the eastward and westward of the main fissures in these Amador
mines. Usually the clay slates may be readily distinguished from the
altered tuffs, but often the slaty tuffs graduate by insensible degrees
into the clay slates, so that no line of demarkation is discernible.

It is rarely that the ore deposits are found in contact with the fine-
grained clay slates, even for a short distance. In fact, the fissures,
where passing through the clay slates are usually destitute of value in
Amador County. This peculiar condition, however, appears to be local,
as in Calaveras County the richest portion of the Gwin Mine is in a
fissure cutting the black clay slates of the Mariposa beds, and in Mari-
posa County the Princeton Mine is wholly in the clay slates of the
Mariposa beds.

In Amador County, however, it seems important to make the dis-
tinction, in view of the results obtained from veins in the clearly recog-
nized clay slates and the pitted slates (altered tuff's). Although the
mines of the old Plymouth Consolidated Company at Plymouth have
not been accessible for many years, the dumps show a large amount of
the tufaceous slate, and there is little doubt these slates accompanied
the ore-bodies. Four miles to the northward, however, the Kretcher
vein of the Bay State Company and the veins of the Rhetta Company
adjoining it on the south, occur in the typical clay slates of the Mariposa
beds, and in these mines are good-sized veins of banded quartz carrying
payable values.

The Dolomitic Vein. — An important geological feature of the Cen-
tral Gold Belt, and one which repeatedly appears from Mariposa to
El Dorado County, is a great, dike-like vein of dolomitic mineral.
This consists of carbonate of lime and carbonate of magnesia — a true
dolomite — and in many places there is also found, in addition to the
above minerals, carbonate of iron, forming ankerite.

This material occurs in great vein or dike-like masses, and is a prom-
inent feature of the lode in Mariposa and Tuolumne Counties and the
southern part of Calaveras County. It also appears near San Andreas,

20 CALIFORNIA STATE MINING BUREAU.

and again near Jackson in Amador County, reappearing near Placerville
in El Dorado County. Mariposite is nearly always present, often in
large amount. Its beautiful green color led early prospectors to believe
it was copper carbonate. The mariposite is not colored by copper, but
by chromium.

The peculiar characteristics of the great dolomitic vein are no better
shown anywhere along its length, perhaps, than at Coulterville and
vicinity. Just below the village on Maxwell Creek, the great vein
crosses that stream, which has cut a gap through it about 100 feet wide.
On the south side of the creek is located the Louisa Mine, and imme-
diately north of it is the Margaret, on the opposite side of the creek.
Where the lode crosses the creek it has a width of 300 feet, and consists
of an immense mass of ankerite, through which is disseminated the
green, scaly mineral, mariposite. Large lens-shaped masses of quartz
outcrop boldly from the ankerite, being somewhat harder than the
latter. The lenses are irregularly distributed, but occur mostly along
the hanging-wall and near the center of the vein. The large veins or
lenses of quartz are separated by equally large or larger zones of the
dolomitic mineral, which is interlaced in every direction by quartz
veinlets and veins of varying size, making the entire mass a mineral
zone or lode proper. One of the quartz lenses is nearly 20 feet in
width, outcrops to a height of 25 feet, and is 300 feet long. A shaft
sunk on the foot-wall side of it to a depth of 60 feet showed it to be
thinning out ; but there is no doubt that it would be found replaced in
depth by another lens of a similar character.

South of this large cropping a small vein branches out into the hang-
ing-wall diabase, striking northward and increasing in width until it
disappears underneath Maxwell Creek. On the opposite side of the
stream a large vein appears, which is apparently the northward con-
tinuation of the one referred to.

Through the center of the lode is a quartz vein 10 to 20 feet in width,
and still west of it is another, but smaller vein. The entire western
portion of the ankerite mass, constituting about one third of the whole
width of the zone, is a perfect network of small quartz veins, stringers,
and small bunches of quartz.

A prominent feature of interest is the union of two of the largest
quartz lenses near the center of the lode by a third large vein, which
crosses the intervening ankerite diagonally. The two large veins are
about 120 feet apart. Beginning near Maxwell Creek, on one of the large
outcrops referred to, a careful examination discovers a seam in the
(juartz, along which gold may be seen almost every foot of the way.
This gold seam can be followed some distance in a southerly direction
to where the diagonal branch above referred to leaves it. This latter
also shows gold along a similar seam, leading to the other large quartz

THE MOTHER LODE REGION — THE SEVERAL DIVISIONS. 21

lens parallel to the first, and here, again, is a gold seam which may be
followed if care be taken. Outside of the gold thus occurring, none was
observed elsewhere by the writer, though it was said that prospects could
be obtained by crushing certain portions of the rock and carefully pan-
ning it.

Southward from the section above described, the several large veins
converge toward a central point on the ridge, which rises higher and
higher, terminating in an immense mass of quartz at its apex. South-
ward from this point the quartz is less prominent and the ankerite con-
stitutes the major portion of the lode until another occurrence of quartz
lenses is reached, which in each case, whether following the lode north
or south, is much the same.

Gold sometimes occurs in the ankerite and mariposite, when seamed
with quartz. A brecciated, crushed condition of this rock seems to favor
the gold, or, at least, rock of this character contains more gold than that
which is massive and solid. The entire mass is low-grade, and ankerite
wholly f^ee from quartz is practically free from gold in this mine.

The characteristics as above described are peculiar to the occurrence
of the dolomitic vein wherever it appears. Often large masses of it
are found crushed, sheared, and altered to talc schist or to a granular
talcose mass, including many angular fragments of crystalline mineral.
In the Rawhide Mine in Tuolumne County was found a notable excep-
tion to the usually observed condition. At one place in this mine the
ankerite and mariposite were found phenomenally rich in gold.

As a matter of course, the description of the occurrence at Coulterville
is not absolutely duplicated anywhere along the lode, but it is typical
in its general features of the dolomitic vein throughout the length of
the lode. In the Pacific Mine at Placerville, the talc schist resulting
from the alteration of the dolomite contains 1 to 2 per cent of iron
sulphide, but whether or not it is auriferous was not ascertained.

The mines of the Central Gold Belt, where not in the dolomitic vein,
occur in black clay slates, in tufaceous black slates, and in amphibolite
schist, and are described under their proper heading.

The East Lode. — The mines of the East Lode, which are found from
6 to 18 miles east of the Central Belt, occur in the slates of the Calaveras
formation and in grano-diorite. Some of the most important of these
mines are found in the latter formation, and a description of their
general characteristics is of interest.

Granite areas in which gold-bearing veins occur are found in Mariposa
County, near Hite's Cove; in Tuolumne County, near Groveland, near
Columbia, and at Summersville and vicinity; in Calaveras County, at
West Point and vicinity; in Amador, at Pioneer; in El Dorado, at
several localities; and in Nevada County, at and near Grass Valley and
Nevada City.

22 CALIFORNIA STATE MINING BUREAU.

Veins in Granite. — In the several granite areas referred to occur a
large number of veins, some of which appear entirely independent of all
others, and in other instances are found systems of connected fissures,
which were evidently produced by a common cause. These veins have
definite characteristics, and the ores are noticeably similar throughout
the entire granitic region referred to. They are usually easily dis-
tinguishable by their physical appearance from the ores occurring in
other formations, whether in the same vicinity or from some distant
point.

The strike and dip of these veins in granite are not at all uniform,
in this respect differing greatly from the veins of the Central Belt,
which almost universally strike west of north and dip easterly. In the
granite areas the veins have no uniform strike, but are found from true
east and west courses around to north, and at all angles between them.
The dip is no more uniform than the strike. Whatever the direction of
dip of a vein, it is usually not persistent at or near any particular
angle, but varies from a low angle to nearly or quite perpendicular.
Not infrequently, in depth a vein will dip in an opposite direction from
that which it has at and near the surface. The veins occur along lines
of Assuring. These fissures are found singly, in pairs, and in many
places as zones of fracture of varying width, comprising several fissures
having an approximate parallelism. These fissures, singly and in
groups, are often planes of movement, as evidenced by slicken sides and
gouge seams. In many cases these zones of fracture are found to
consist of crushed granitic material, greatly altered, and in some
instances containing vein quartz in a granulated condition, indicating
that a movement of the rock-masses has taken place subsequent to the
deposition of the quartz. In certain more rare cases, this brecciated or
granulated quartz has been cemented by a still more recent infiltration
of silica. In these crushed zones the feldspars are thoroughly kaolinized;
the bi-silicates are altered to chloritic mineral, and the whole mass is
soft and, when wet, sometimes mushy, forming dangerous ground to
mine. Often it is gold-bearing, though seldom rich.

In the same fissure plane or zone are found the concentrated mineral
deposits forming the ore-bodies proper of the mines. In some places
they lie at the side of these crushed, partially silicified zones, either in
direct contact with them or separated by a strip or wedge of hard
granite, but little altered. In other instances they are found as sepa-
rate ore-shoots, connected with the previously described crushed zones
only by a clay seam. Other masses of quartz occur in these fissures,
which contain very little of either gold or sulphide mineral.

These veins are undoubtedly the result of substitution of silica, cal-
cite, and other minerals for the original soluble constituents of the
granite, having been conveyed to the point of deposition by mineral

THE MOTHER LODE REGION — THE SEVERAL DIVISIONS. 23

solutions, probably derived from a deep-seated source. The most com-
plete replacement has evidently occurred where the Assuring and crush-
ing have been greatest. The vein quartz is found exhibiting every phase
of condition from a partial alteration of the granitic mass, almost a
normal granite (though the feldspars are always carious, and a small
percentage of finely divided iron sulphide may usually be observed),
through the various stages of transition, finally reaching the most com-
plete alteration to crystalline quartz, sometimes heavily impregnated
with the sulphides of iron, lead, copper, zinc, and silver, with gold and
other minerals more rare. Calcite is a frequent accompaniment, both
in the quartz and in the crushed zones of granite. The vein quartz
occurs in a variety of conditions — as a vitreous, colorless, granular rock ;
a milk-white, semi-greasy kind ; a bluish-black variety, usually vitreous ;
also in alternating bands of bluish and white rock, and as granulated
quartz. All of these varieties are gold-bearing, and again all kinds are
barren. All are associated with sulphide minerals, and all again occur
with scarcely a trace of them. The banded varieties are usually of fair
grade in gold, and the appearance of galena is often an index of value.
Some of the zinc ores are also high-grade. The sulphide minerals con-
tain from $50 to $1000 per ton in gold, and some are also correspond-
ingly rich in silver, though the silver contents are usually relatively
small. The sulphides are pyrite, marcasite, mispikel, chalcopyrite,
galena, blende, and pyrrhotite. The latter is peculiarly characteristic
of granite formations throughout California, particularly in the ore-
bodies of larger size. Tellurides of gold occur sparingly in several
localities. The ore-shoots vary greatly in width and length, though the
veins sometimes have a width of 30 feet or more, as in the Black Oak
Mine in Tuolumne County. Ordinarily, however, the shoots are less
than 100 feet in length and average between 6 inches and 2 feet in
width. Often the lenses have an average length of 20 feet, but succeed
each other immediately, the ends often overlapping, thus forming prac-
tically a continuous shoot of considerable length.

Occasionally are found two veins approximately parallel and sepa-
rated by 1 to 4 feet of granite in a more or less advanced condition of
alteration, as is the case in the Good Hope Mine, near Ferris in River-
side County. The branching tendency of the fissures is a pronounced
characteristic. Usually one wall at least is well defined — generally the
foot — the zone of fracture and crushing extending to various distances
into the hanging-wall. Now and then a perfectly defined hanging-wall
will be found, but progressing along this wall it is seen to diverge gradu-
ally from the plane of the foot and its influence as a bounding plane is
lost, another slip or wall taking its place. This continues indefinitely
until the identity of the entire vein is lost in the numerous branching
cracks which extend into the granite. Often a well-defined vein several

24 CALIFORNIA STATE MINING BUREAU.

feet in width will thus pinch out to the merest crack, in which is found
no sign of clay or of movement, and it requires the most careful obser-
vation to follow it at all ; but usually by persisting in the general direc-
tion of the course of the vein it may be found to reopen and new shoots
of ore found. Sometimes, however, after drifting fruitlessly some dia- Ij
tance, a cross-cut is advisable. In some instances these pinches are
several hundred feet long and the ground very hard.

The formation of many short shoots of rich ore in portions of the
fissure where the walls are several feet apart is an interesting feature.
It is not uncommon to find a wedge of quartz forming on the foot-wall,
which gradually widens to 1 or 2 feet when it leaves the foot- wall, crosses
the fissured zone at a low angle, and joins the hanging-wall, where it
thins out and is lost. Between the short shoot of ore thus formed a^id
its parting from the foot- wall there may be found several stringers of
quartz parallel with the foot, or the entire space may consist of a reticu-
lated group of small veins and seams, while along the foot-wall a second
wedge-shaped vein of quartz will appear, which will repeat the peculiari-
ties of the shoot adjoining as described. The granite adjacent to the
vein, and occurring as horses within it, is frequently gold-bearing to a
considerable extent, sometimes in sufficient quantity to be visible to the
naked eye.

It is the custom to sort out the granite as waste, but it should be done
with caution, for it not infrequently pays to send the entire contents of
the vein to mill, when in the pay shoot. The fact that several old dumps
have been worked at a profit is evidence that early methods were careless
in this regard. In some respects these mines are worked at a disad-
vantage, for it is easy to lose the vein where a pinch occurs, and it has
led in numerous cases to the closing of what are probably good mines.
What has been described as occurring along the vein horizontally is
equally applicable to the fissure in depth, and a pinch in the shaft does
not signify that the limit of the vein has been reached any more than it
does when occurring in the face of a drift.

These disadvantages are greatly offset, however, by the high grade of
ore, which is uniformly much higher grade than that in larger veins in
other formations. Often the ores from the veins in granite may be
shipped to distant smelters with profit after rough sorting.

Dikes are of frequent occurrence throughout the granite area in the
neighborhood of the mineral belt. They are of various types, but the
most common are granitic dikes of coarse crystallization and dark green
diorites of fine grain, extremely tough and hard. The former are char-
acterized by the occurrence of masses and crystals of albite, tourmaline,
and biotite. The peculiar, interwoven, grate-like structure of quartz
and feldspar, known as graphic granite, is of frequent occurrence in
these dikes. These granitic intrusions are usually older than the veins.

THE MOTHER I.ODE REGION — THE SEVERAL DIVISIONS. 25

though there are exceptions. The diorite dikes, however, are generally-
younger and cut the veins. The dikes, as a rule, cross the line of strike
of the veins, though not always. Whether or not these dikes have any
important influence on ore deposition is a question.

In some instances ore-shoots are found lying with the granitic dikes,
the downward pitch of the ore-body being coincident with the dip of the
dike. The influx of large quantities of water is a usual accompaniment
of the development of these veins. It often comes with a rush at unex-
pected times. A mine may be developed to considerable depth and
have encountered but little water, when without warning a blast will
break into what is called by the miners a reservoir or pocket, though
usually, in fact, a system of fissures filled with water derived from the
surface. The deeper the point in the mine at which these water crevices
are struck, the greater the force of the water. Often the lower levels
are completely flooded, and weeks are required to pump out the water,
but in time the reservoir is exhausted, and things resume their usual
condition. Another water-rush may not occur in many months, and
again in some places they have been found in quick succession. In one
instance a water crevice was broken into in the Black Oak Mine in
Tuolumne County at a depth of 600 feet. With considerable difficulty
a bulkhead was constructed, and the pressure gauge indicated at one
time a standing pressure of 180 pounds to the square inch, indicating
that the height of this reservoir was not less than 400 feet. The flow
being controlled by means of a valve, the pumps in time removed the
water and a normal condition was again reached. After several months
the bulkhead was torn out and a round, of holes was drilled in the face
and discharged, upon which the water again rushed into the mine work-
ings in as great volume as before. The probability is that in some
manner the vent to the reservoir had become clogged and the flow of
water stopped. The force of the blast removed the obstruction, and the
water again poured into the mine workings, but it finally was drained to
a considerable extent. This shows the necessity for abundant capacity
to handle water. Some claim that large flows of water are an indica-
tion of valuable ore deposits, but there is really no apparent relation
between ore deposits and large flows of water. The ore was deposited
by ascending currents, and the water found in mines is always found
coming down from the direction of the surface. Sometimes water may
be seen bubbling up from the lowest levels of the mine as though from
an ascending current, but a case of this kind is due to hydrostatic
pressure, the water flowing in coming from some point higher, through
a series of connected cracks or fissures.

A peculiarity of these veins in granite near the surface may often be
observed in the occurrence of open cracks traversing the vein in a hori-
zontal direction, reaching from wall to wall, and dividing the vein into

2B CALIFOKNIA STATE MIiNING BUREAU.

l)locks by a series of floors, as it were, at quite regular intervals of a foot
or thereabouts, depending somewhat on the width of the vein. The
blocks are separated by 1 to 4 inches of space, in which have accumu-
lated clay and grit, quartz crystals, iron oxide, and other secondary
products and gold. The amount of gold is largely in excess of the
amount found in an equal weight of quartz of the vein itself in many
cases. This peculiar occurrence is undoubtedly due to a sort of molecu-
lar expansion of the granitic mass, chiefly due to the alteration of the
feldspars, and in a less degree possibly to the change which has taken
place in the other constituents of the granite caused by surface decay
and meteoric agencies generally. It is an interesting fact, and aftbrds
food for study and investigation.

The occurrence of gold in the silt-like material lying on these floors
may be due partly to the quartz itself, but more probably comes from
the oxidized sulphides, and also in part perhaps by infiltration from
the selvages of the vein, if not from the granite itself, which may have
become gold-bearing by impregnation from the fissure. Attrition, due
to movement, may also have been partly responsible for the occurrence
of this gold. When the oxidized zone is passed and the granite becomes
normal, these floors no longer appear.

In many places the quartz is perfectly free from both walls, and again
but one wall is free, the opposite side being frozen. In an equal num-
ber of cases the vein is frozen on both walls. These variations are not
constant, for a vein may be free at one place and frozen in another.
These changing conditions may be considered as indicating something
of the relation of the original fissure to the ore deposit. Where both
walls are free, it is not unlikely that the ore is filling the space bounded
between two fissures. Where one wall is free the mineralization has
progressed along one side of the fissure plane only; and where both
walls are frozen, it would seem to indicate that ore deposition progressed
outwardly from a single crack, or possibly, in the case of a large ore-
body, the mineralization has impregnated the walls beyond the limiting
planes of the fissured zone, to an extent sufficient to constitute ore, and
has stopped only when the mineral solutions were unable to penetrate
farther from the fissure plane itself.

METHODS OF MINING.

The mining methods in vogue on the Central Lode of California are
not, in the opinion of the writer, those calculated to produce the best
results, when viewed from the standpoint of economy. They are, with
few exceptions, the methods of thirty, of forty, and of fifty years ago, and
some of the practices are so primitive in their nature as to savor of
past centuries rather than of decades.

THE MOTHER LODE REGION — METHODS OF MINING. li

A policy which obtains throughout the mining districts of California
is that of demanding prompt returns from ore development, which is of
course very desirable, but which in many cases works ultimately to the
disadvantage of the owner, and the manager or superintendent is so
completely handicapped that he is unable to make substantial head-
way. There are certain districts where this demand for "immediate
returns" does not act so disadvantageously, but in the mines of the
Central Lode it is undoubtedly a short-sighted policy. The reason for
this will become apparent when it is understood that with few excep-
tions the ground is heavy — often swelling and crushing the heaviest
timbers. The usual practice is to drive a cross-cut or drift from a
station at the shaft to the vein. This may or may not at once
encounter ore; if not, a drift is driven along the fissure, which must be
timbered in the most substantial manner. These drifts are usually
not less than 7 feet high, 4 to 5 feet wide at the top, and 7 to 8 feet at
the bottom. These dimensions are all inside the timbers. It usually
makes little difference whether the cutting is in ore or not, the ground
is generally heavy. The fissures are often from 10 to 40 feet wide, and
the miners (of Amador County particularly) are well acquainted with
the danger, difficulty, and expense attending this kind of mining. As
soon as pay rock is encountered it is hoisted and sent to the mill, and
the drift continues, while overhand stopes are started and development
proceeds. It may be several hundred feet to the limit of the property,
and is often over 1000 feet, and this heavy swelling — sometimes run-
ning— ground must be kept open until the entire level has been explored
and the ore to the level above all extracted and sent to the surface. An
idea of the character of some of this ground may be gained from the
statement that in a certain instance a drift of usual size being driven
a distance of 200 feet, at the rate of 5 feet or more daily, under con-
tract, could not be completed before it became necessary to return to
that portion first driven for the purpose of retimbering. The timbers
employed in holding ground of this character are usually 20 to 30
inches in diameter, and it is no uncommon thing to see these immense
logs, a few weeks after being put in place, split, crushed, and broken as
though they were incapable of offering any resistance to this all but
irresistible force.

The advisability of cutting the main gangways in the hard rock of
the walls, either foot or hanging, and reaching the vein by a system of
cross-cuts, is advised. This has not, as yet, at this writing, been
attempted, but its feasibility and desirability can readily be appreciated
when the character of the main fissure, as above explained, is understood.

These main gangways, being driven in, say the foot-wall, should have
cross-cuts extending at right angles to the direction of the main gang-
way. These should be disposed at stated intervals for the purpose of

28 CALIFORNIA STATE MINING BUREAU.

prospecting the fissure and to render accessible the ore discovered. In
slate, the main gangways should be at a distance of 40 to 60 feet from
the vein — where in greenstone, they may be driven nearer the vein. The
cross-cuts should be driven at stated intervals, a greater or less distance
apart according to the character of the ground adjacent to the vein-
When the ground is very bad, the cross-cuts should be closer, and when
less so, at longer intervals. In most cases, if driven at intervals of 240
feet, the distance will be found convenient. Raises should always be
put through, connecting with the level above, before stoping is com-
menced. Very often this important matter is neglected, owing, as pre-
viously stated, to a desire to realize a profit on the ore as quickly as
possible. These raises should be put in about 60 feet apart; this,
beginning 30 feet from the point where the cross-cut reaches the vein,
will admit of four raises within the 240-foot section suggested, the vein
being worked 30 feet each side of the raise.

When putting through raises, it is really an economical plan to sink
a winze from the level above to meet the raise. By this means ventila-
tion will be more quickly obtained, and the additional work which men
can accomplish will soon pay for the increased cost of sinking the
winze. Men will not and cannot perform the best work most expe-
ditiously in a foul atmosphere, though this fact seems to be lost sight
of by many mine-owners.

In addition to the great disadvantage of foul air, when the raises are
not put through, the heavy timbers must be hoisted through the raise
into the gtopes by means of block and tackle at great expense of time.
If the raise were through, the cost of handling these great timbers would
be very materially reduced by lowering them through the raise from
the level above to the floor of the stope where they are to be placed in
position.

With the lateral drifts and cross-cuts completed, and drifts driven on
the vein, with raises through to the next level above, the work of stoping
can be carried on at as many points as may be desired, and in a few
weeks, or months at most, the greater portion of the excavation made on
the vein, where not filled, will collapse and be closed up forever. This
works no harm or inconvenience, as the main lateral drift remains open.

When operating in this manner, filling for the stopes may be taken
from the hanging-wall by driving an inclined raise into it and opening
out a chamber. The rock broken in these chambers will pass by gravity
down into the stopes beneath and fill them, little or no shoveling being
necessary. This method of mining and filling, when properly carried
out, will prove more safe and far less expensive than some of the methods
heretofore employed in California mines. In some mines, if stoping be
expeditiously prosecuted in the manner above suggested, no filling will
be recjuired, the timbers affording all the support necessary, but in most

THE MOTHER LODE REGION — METHODS OF MINING.

29

cases filling of the stopes is advised. Where the hanging-wall country-
adjacent to the vein has a tendency to cave, it may be that the inclined
upraise for the purpose of obtaining filling for the stopes may be inex-
pedient. In that case, a horizontal cross-cut may be driven to the solid
ground of the hanging, that portion nearest the vein being securely
timbered. The filling must then be distributed by means of wheel-
barrows.

fT]Gt}^od of vVorkfino \/eiris in ^vV^l (ir}o ground,

Fig. 2.

These filling chambers may be vi^orked with hand or power drills,
large or small, as seems desirable. One of the greatest items of mining
expense, as now practiced, is that of constantly relieving swelling or
running ground, and retimbering. When the ore-shoot is attacked in
sections by cross-cuts from the lateral drift, any particular section heed
remain open only a few months at most, instead of two, three, or more
years, as now.

30 CALIFORNIA STATE MINING BUREAU.

Another advantage may be derived b,y driving an intermediate level
midway between the main levels, if the ground is particularly bad, and
connecting with the cross-cut or gangway beneath by a raise. In this
manner the floor of the lower main level need only be maintained about
half the time that would be necessary if all ore were sent down to the
main level through a mill-hole extending upward 100 feet more or less,
and connecting two main levels. This plan would, of necessity, require
that a raise be cut through solid rock from the vicinity of the main
gangway to the foot-wall of the vein, reaching it about midway between
two levels. Each of these raises would have an approximate height of
45 to 60 feet, and would cost, perhaps, when timbered, $500; but the
expense of keeping open the level in the vein would soon offset this
expense if the ground were very bad. As a matter of course, the super-
intendent must determine when an intermediate level and auxiliary
raise are justifiable. His experience with the ground in the fissure will
dictate whether the plan suggested is advisable or not. The sketch
(Fig. 2) on page 29 illustrates the idea.

Timbering. — The timbers employed in the mines of the Central Lode
are uniformly large — 18 to 30 inches in diameter — and the method of
framing and placing them varies somewhat, but is usually, in the larger
stopes, some modification of the system known throughout the world as
the Nevada square-set. The placing of these timbers is accomplished
often under great disadvantage, and, in some instances, with consider-
able evident danger. The men selected for this work usually represent
the finest type of physical manhood, for no others could accomplish
the arduous task expeditiously. As to the relative merits of the respec-
tive methods of framing these heavy timbers, it seems only necessary
to say that those systems involving the least framing with ax and adz
underground, and consequent smaller loss of time in placing timbers in
position, are the methods best adapted to regular practice.

In some mines an objection is raised to the emplo3'ment of sills on the
main floor of a level, for the reason that the sills rot before the stopes can
be carried through from any level to the next above. In most cases there
is no excuse for this. A reprehensible practice, which is found almost
universal in these mines, is that of attempting to carry up stopes of
too large a superficial area, and this practice is responsible for some
disastrous caves which have occurred in various mines. A stope of
smaller superficial area can generally be carried from one level to the
next above more quickly and safely than a large one, and in most cases,
even by the present "old-fashioned" methods of mining, a stope of
small sectional area may be carried through in a few months — long
before the sills become weakened by reason of deca3\ If the develop-
ment of the mine were carried on well in advance of the extraction of the
ore, it would not be found necessary to open these large stopes, as a num-

THE MOTHER LODE REGION — METHODS OF MINING. 31

ber of smaller slopes would supply the same amount of ore daily as is
usually drawn from one, two, or three large stopes, and it would be
found that ultimately the cost would be materially less, as in most cases
there would be no loss of ore, no disastrous caves, and work could be
accomplished more expeditiously and more cheaply.

Filling. — There are few veins on. the Central Lode where, by present
mining methods, filling is not absolutely necessary, though by the adop-
tion of the lateral foot-wall gangway system heretofore suggested, in
some of the smaller mines, filling might to some extent be dispensed
with, the walls being allowed to collapse after removing the ore. Mate-
rial for filling is usually obtained from cross-cuts and drifts driven in
prospecting, and from chambers cut in the walls of the veins — generally
the hanging-wall. There are few veins on the lode so small as to make
enough waste in sloping to fill the excavation. Ordinarily, all the
rock removed from the pay-shoot goes to the mill, and filling must be
obtained elsewhere. In some of the larger mines, where the veins are of
great size — 40 to 100 feet or more in width — it is not uncommon to find
the entire vein removed for a distance along its strike equal to and often
much greater than its width, the entire area overhead resting upon the
props reaching from the topmost set of timbers to the roof. There may
be three, four, or more floors in place, and the stope may be found filled
from the sill floor to within a floor or two from the top; but it is clearly
evident that in a stope of the size indicated, this filling can afford but
little if any support to the hanging-wall, and none at all to the back of
the stope. Failure to recognize this fact has resulted disastrously in
more than one mine. The- filling must be placed in such manner as to
support the back of the stope over as large an area as possible, and a
portion of this filling at least must be placed by hand, for it is clearly
evident that should any subsidence occur in a stope approximating 100
feet square, timbers cannot be depended on to support the great weight.
In a stope having a width and length of 100 feet and carried up four
floors in height, there would remain between the top set and the floor of
the level next above (65 feet) not less than 50,000 tons of ore. Should
this become "dead weight," each post of the sets in place would have to
sustain a load of several hundred tons of ore in addition to the weight
coming from ore and filling in levels above, and to this must be added
the greater pressure coming from the direction of the hanging-wall.
This weight, or pressure, will vary greatly in diflerent mines, depending
upon the character of the ground, the condition of the walls, and to no
small extent upon the angle of dip of the vein. Were the enormous
weight of this great shifting mass of rock equally distributed, there
would be less probability of a cave; but often, the weight being trans-
ferred from point to point, owing to the mobility of the ground, the
pressure upon some given point becomes greater than the timbers can

32 CALIFORNIA STATE MINING BUREAU.

sustain, and a single line of sets once forced out of position renders the
remaining sets less secure than before, and general collapse results;
and most miners are familiar with the dangers and extraordinary
expense incident to the recovery of a caved stope and the extraction of
the shattered masses of ore from the zone above the cave. In veins
having vertical walls the danger of caves is much lessened, but the
mines of the California Gold Belt dip at all angles ranging between 30
and 85 degrees, the greater number being between 45 and 70 degrees, below
the plane of the horizon. This being the case, the pressure upon timber
sets is exerted diagonally and not directly downward upon the posts of
the sets. Naturally this renders the square, or rectangular, sets less
capable of sustaining the weight and pressure. In some mines diagonal
braces are set in to take this hanging-wall pressure more directly, but
timber will not hold it.

In consideration of the above facts, the absolute necessity of filling
becomes apparent, and the necessary preparations to this end should
always be promptly made in order that the filling of the stopes be not
too long delayed. Filling must be carried on contemporaneously with
ore extraction; and in stoping, the excavations should be carried
upward in sections of relatively small superficial area, the filling being
packed as close to the back of the stope as possible. Where the veins
do not greatly exceed 15 feet in width, the conditions are essentially
changed, as in such cases the stopes may be timbered with stulls set
slightly above a right angle to the dip of the walls. Most mines, where
the walls are suflBciently firm, are timbered in this manner when the
distance between walls admits of it. The conditions are so variable in
these different mines, and often in different parts of the same mine,
that the methods of timbering embrace almost every phase known in
practice. The various methods of timbering employed in California
mines and elsewhere were described and illustrated by the writer in
Bulletin No. 2 of the California State Mining Bureau, February, 1896.
See also method of stoping and filling at Eagle-Shawmut Mine, Tuolumne
County, in this bulletin.

Drainage. — A very important factor in the economy of mining is the
water encountered in the underground workings, and an ever-present
question is the most inexpensive method of removing this incoming
water from the mine. It is accomplishai in three ways: — by natural
drainage through tunnels; by means of pumps, or by bailing. This
subject has been exhaustively treated in Bulletin No. 9 of the State
Mining Bureau, by Hans C. Behr, M.E., and it is unnecessary to more
than refer to it here. On the Central Gold Belt, and in fact throughout
California, the large majority of mines bail water from sumps at the
bottom of the shafts, or from tanks situated at various levels, where
water descending from the surface and upper levels is caught.

THE MOTHER LODE REGION — METHODS OF MINING. 33

Where the inflow of water is large, and the shafts are poorly equipped
with hoisting machinery, with crooked, rough tracks or skids, the prob-
lem of bailing water, hoisting ore and waste, and carrying on develop-
ment work — particularly that of sinking in the shaft — becomes a serious
one, and sometimes it necessitates shutting down all work in the mine
except that of sinking. Where this very undesirable combination of
conditions is found, steam pumps are the most satisfactory, and it may
be said that there is a growing tendency to the more extensive employ-
ment of steam pumps in mines of the Pacific Coast. In many cases
steam pumps are found replacing the Cornish pumps.

In this connection, the following contribution will be of interest to
mine managers generally. It was written by request for this bulletin
by Mr. J. Renshaw, one of the foremost hydraulic engineers of the
United States, and who has had a very extensive experience in mine-
pumping operations where they were conducted on a large scale:

SOME OBSERVATIONS AS TO THE RELATIVE ADVANTAGES OF CORNISH AND
DIRECT-ACTING DUPLEX PUMPS FOR PERMANENT MINE PUMPING.

By ^Ir. J. Rexshaw, of Denver, Colorado.

(Written by request for this Bulletin.)

The following comparisons of the relative advantages of the higher grades of direct-
acting, duplex steam pumps as compared with the old and well-tried Cornish system,
refer to permanent pumping plants for mines in which the water is below the tempera-
ture of about 70° or 75° Fahr. When the water is above that temperature, it is evident
that tlie exhaust steam from the direct-acting steam pumps cannot be advantageously
disposed of, and either the Cornish pump, or some other plan in which the motive
power is located at the surface, must be used.

Up to 1878 some one of the various modifications of the Cornish pump was exclu-
sively used both in Europe and in this country. In that year, a simple cylinder, non-
condensing, single-plunger pump at the Ontario Mine, Utah, with 12-inch plungers,
24-inch stroke, and 500 feet vertical lift, was altered into a compound, condensing pump
by the addition of an expansion cylinder and a spool-shaped bushing put in the
original cylinder, the space between the original bore and the outside of the bushing
forming a steam jacket. This pump was, we believe, the first attempt toward a higher
grade direct-acting steam pumj) located in lower workings for permanent mine pump-
ing. It was thoroughly tested, first by the writer and then by the designer of a Cornish
pump which had been selected by the writer to be put in, should the other not prove
economical. It met with strong opposition, mainly from the builders of the Cornish
pumps, both in California and the East, and with much skepticism of Eastern mine
operators, principally, we think, with the belief that steam could not be conducted in
pipes a long distance without a ruinous loss by condensation, and this idea held among
many not familiar with the results of the compound, direct-acting, condensing steam
pumps that had been put in, until 1884 and 1886, when they were put in a mine at
Leadville and in one in Ishpeming, Mich., since which time very few Cornish pumps
have been built in this country.

In 1882 or 1883, a Cornish pump was built for the Ontario Mine, which is no doubt the
best example of that style of pump built, at least in this country. The writer had no
opportunity to test it, but the manager of the mine said that he thought it saved a little
in steam ever the crude, direct-acting, condensing steam pumps that had been installed
in that mine. When asked if he was sure as to any saving in steam, he replied that he
was not, and later advised a mine operator in Leadville to put in the direct-acting,
duplex condensing pump as against the Cornish pump, as the difference in cost more
than balanced the possible saving in steam.
3 — MB

34 CALIFORNIA STATE MINING BUREAU.

We know of no publicly reported experiments having been made to determine the
amount of condensation in steam pipes until a series was made by the New England Board
of Underwriters, and reported in the transactions of the American Society of Mechan-
ical Engineers. The result then had, on pipes covered with one inch of hair felt and
that by a thickness of burlaps, coincided almost exactly with what we had determined
at the Ontario Mine with the same thickness of hair felt covered with 10-ounce canvas.
At the Wolftone Mine at Leadville, the condensation in 585 feet of 4-inch wrought-iron
pijie, covered with ^ inch of asbestos paper, 1 inch of hair felt, and this covered with
painted 10-ounce canvas, was 57.75 cubic inches per minute, or 8.396 cubic inches per
minute for each hundred square feet of external pipe surface.

Judging by past experience, there is little difference in "duty" between the best
examples of Cornish pumps and the best examples of direct-acting, compound con-
densing pumps, each, for say 1000 gallons per minute lifted 1000 feet vertically.

With triple-expansion, direct-acting, condensing pumjis with the initial steam pres-
sure at the pump at 140 pounds, and the pump running at say 125 feet piston speed, the
comparison would undoubtedly be much in favor of it over the Cornish pump.

There are, however, othel- very important considerations to the mine operator as to
the relative advantages of the two systems of pumping, besides a little difference in the
steam economy. On a basis of 1000 gallons lifted 1000 feet per minute, the installed
cost of the direct-acting pump will not reach 10 per cent of that for the Cornish pump.
In most cases the working-out of the mine beneath the foundations of the Cornish
pump engine will, by settlement, throw it out of line, it not being a self-contained
machine like the direct-acting pump. So, also, with the "pit-work."

Another very important consideration is the expansibility — if we may so call it — of
the two systems. When the size of a Cornish pump is to be determined, a large margin
for increase of water through greater depth or side workings has to be allowed for, and
what this margin is to be is difficult to determine. As a rule, but one Cornish pump;
can be installed in the one-pump compartment of the shaft, and it cannot be replaced I
by another without allowing the shaft to be flooded ; and it is a question if it could bej
taken out as fast as the water would rise. This would depend upon the amount of |
ground worked out. Frequently there is allowed a greater margin for increase of water!
than afterwards proves necessary, either from the ore-body giving out, or less waterj
being encountered than expected. The interest on investment, and wear and tear of aj
larger machine than necessary, are important considerations. Or, it may be years be-|
fore the full capacity of the pump is called for. On the other hand, if too small a pumpi
is put in, a new shaft has to be put down in which to install another and larger pump.j
Thus, the size of the pump has to be determined once for all.

Not so, however, with the direct-acting pump. They need only to be bought as depth!
is attained or increase of size becomes necessary. If the pump i)roves too small, a|
larger one may be installed on the pump station and the smaller one moved down to aj
lower level where less ground has been opened, and so on, making pump stations every
500 or 1000 feet. If the column pipe for the first pump put in is not of sufficient size]
for the larger pump, there is generally room enough to put in a larger one, and th(
smaller pipe then used below for the small pump. The expenditure for pumps ma>
thus be by increments as needed.

As we have said, pump-shaft compartments are seldom large enough to install bu'
one Cornish pump line, and "the eggs are all in one basket"; whereas with direct
acting pumps, two may be installed in the one station, both connected to one columi
pipe or each with its own, and in case of necessary repairs, one may be stopped and thi
other started. It is very comfortable for the mine operator to feel thus secure.

If there are two or more compartments to the shaft, one of which is for pump, piping
and ladders, that compartment should be well bratticed from the adjoining hoistiu}
compartment. The heat radiated from even the well-covered steam pipe tends to mak
that compartment an "uptake" and the hoisting compartment a "downtake," anc
thus fairly good ventilation is to be had in the pump station or level.

We need hardly say that it is important to keep pipes and their bearers snugly to tlb
sides of the shaft, so that there will be left a clear run for the rising of warm or foul air

When, through the decomposition of pyrites or other minerals, the water is too ho
for the condensation of steam below, then either compressed air may be substituted fo
steam, electric, or rope-driven power pi;mps, or the Cornish pump must be used. Wit)!

THE MOTHER LODE REGION — THE COST OF MINING. 35

the utilization of mountain streams as a source of power, and either electricity or com-
pressed air to transmit it, comes a new feature in mine pumping which will be more
and more used, as in most of the metal-mining locations the cost of fuel is a "burning "
question. The transmission of power to the station pump by electricity would present
a simple solution of the difficulty were it not that the speed of the pump has to be
varied, either because of increase of water by ground opened, or by the seasons affecting
the surface water. We think this difficulty can be overcome without uselessly expend-
ing power.

The above is given as a summary of the relative advantages of the two systems of
mine pumping, for a part of which we have to rely upon memory, but we are substan-
tially correct.

The Diamond Drill. — In a number of mines of the Central Lode the
eflficiency and great desirability of the diamond drill as a prospecting
device has been repeatedly demonstrated. It has been used with good
judgment and excellent results at the mines of the Wildman Company
at Sutter Creek, and also at the Baliol Mine near Sutter Creek, Amador
County; in the Lightner Mine, Angels, Calaveras County, and elsewhere;
and there seems to be a more general disposition to employ this machine
for the purpose indicated, as by its means ore-shoots may be located at
a distance from the main mine workings, either in the hanging or foot
wall, at a minimum of cost. Not only is the proximity or the absence
of ore demonstrated, but the character of the barren rock through which
workings must be driven in order to reach such deposits is also ascer-
tained, and the cost of development thus approximately determined.
The diamond drill may also be employed in locating, old workings,
making connections for ventilation, and even in draining old flooded
workings. Its use cannot be too highly commended in a region where
there are broad zones in which occur ore-shoots scattered at irregular
intervals, and this feature is particularly characteristic of large portions
of the Central Gold Belt. The diamond drill may also be used to
advantage in both the gold and copper mines of the West Lode.

THE COST OF MINING.

Another consideration is the cost of mining. This is something which
can never arbitrarily be determined until the character of the mine has
been demonstrated. The width and length of the ore-shoot must be
known, and the character of the walls ascertained. The probable
quantity of water which will have to be handled is always problemati-
cal, and, as a matter of course, the character of the walls and vein
material itself will determine the method and expense of timbering. It
is not uncommon to hear it said that in California mining and millino-
can be accomplished, under favorable conditions, for less than $1 per
ton, but these conditions so rarely obtain, even in California, as to
scarcely be worth mentioning, for they by no means constitute or illus-
trate the typical features of California mining. There are mines in
slaty rocks not particularly hard, where the veins are 3 to 7 feet in

36

CALIFORNIA STATE MINING BUREAU.

width, which, being worked through tunnels and having free water
power, are operated at a very low cost, but even this class of mines does
not represent the majority — indeed, such constitute a very small minority.
In the greater number of mines in this State operations are conducted
through shafts, which necessarily increase the expense of mining. In
the Central Gold Belt the mines vary so greatly in size, depth, char-
acter of ore and wall-rocks,, and quantity of incoming water, that a
statement of cost would convey but little information, and comparison
would be valueless unless accompanied by a complete knowledge of
existing conditions and an itemized cost-sheet. At a number of larger
mines elaborate cost-sheets are kept, and to a number of these the
writer has been given the freest access. The cost of mining in the
larger mines, under ordinary conditions, may be fairly represented by
the cost-sheet of the Wildman Company at Sutter Creek, which has
been kindly furnished by the superintendent, Mr. John Ross, Jr.

DETAILED AVERAGE COST OF MINING ONE TON OF ORE

For the Years 1896, 1897, 1898, at the Mahoney Mine of the Wildman Company.

Total Cost for
134,886 Tons.

Cost per
Ton.

Timbers

Spiling

Lumber - -.

Charcoal ..-

Candles

Powder... -..

Fuse

Caps

Water

Freight

Iron -

Steel and steel rails

Hardware

Oil

Grease and tar

Coal -

Miscellaneotis

Power-drill machinery

Surveying

Cement

Insurance ...

Taxes

"Wire rope

Office supplies

Superintendence and labor

Dollars.
24,499 18

4,913 0.5

1,017 57

1,242 01

1,840 59

4,386 75

780 16

186 05

7,538 00

1,338 42

1,224 24

1,417 27

3,139 48

775 37

117 27

229 57

3,241 69

2,346 90

667 50

15 00

103 77

737 63

636 28

97 67

160,003 58

Cents.
18.163

3.642

.755

.92

1.365

3.252

.578

.138

5.589

.992

.908

1.05

2.328

.575

.087

.170

2.403i

1.740!

.4951

.01l|

.077|

.547!

.4721

.072i

118.62ll

$222,495 00

164.95Ci

I

John Ross, Jr., Superintendent.

THE MOTHER LODE REGION — THE COST OF MINING,

37

DETAILED AVERAGE COST OF MILLING ONE TON OF ORE

For the Years 1896, 1897, 1898, at the Mahoney Mill of the Wildman Company.

Shoes

Dies -- --

Screens

Quicksilver

Hardware

Water for power...'

Freight

Cyanide potassium

Wood

Charcoal, iron, and steel

Oil

Grease

Lumber

Miscellaneous and coal..

Timbers.

Assay supplies

Office supplies

Expressage, bullion

Hauling and loading sulphurets

Silver-plating plates

Insurance

Taxes

Plates

Superintendence and labor ..

Total Cost for
134,901 Tons.

Cost per
Ton.

Dollars.
2,310 00

Cents.
1.712

2,078 63

1.541

441 97

.328

870 14

.645

1,199 05

.889

10,699 60

7.931

1,064 00

.789

162 00

.120

220 88

.164

97 74

.073

63 95

.047

23 13

.017

67 34

.050

1,529 46

1.134

17 95

.013

516 59

.382

275 73

.204

391 16

.290

2,354 65

1.746

281 50

.208

423 14

.314

701 11

.520

86 49

.064

16,791 58

12.447

$42,667 79

31.628

The above cost includes all repairs and equipment.

John Ross, Je., Superintendent.

Following is the cost-sheet of the Gwin Mine, Calaveras County, for
the month of July, 1900, which is kindly furnished by Mr. J. J. Craw-
ford, secretary of the company:

38

CALIFORNIA STATE MINING BUREAU.

DETAILED COST OF MINING, MILLING, AND SULPHURETS AT THE GWIN MINE FOR
THE MONTH OF JULY, 1900.

Mining

And Trans-
porting to Mill
7,965 Tons.

Cost per Ton.

Milling

3,000 Tons.

SULPHUKETS

Ooncentra-
lion, Trans-
portation and
Reduction
Charges on
108.545 Tons.

Cost per Ton. Cost per Ton.

San Francisco oiiice — salaries, directors' fees,

and expenses --.

Management

Mine oflfice — salaries and expenses

Labor

Water

Electric light --.

Timbers

Lagging

Wedges

Lumber

Powder

Fuse

Caps

Candles

Drill steel.

Iron and steel

Tools and implements

Hardware

Charcoal

Oils and lubricants

Shoes and dies

Screens

Chemicals

Average loss of quicksilver of four years

Miscellaneous supplies.

Survej'ing

*Assaying _ apportioned

*Blacksmith shoj) apportioned

*Pumps and repairs apportioned

*Power drills and repairs apportioned

Legal e.xpense

*Equipment and construction.. .apportioned

§ Development apportioned

Taxes apportioned

Stable and animals apportioned

Comi)ressor— labor and supplies

*Compressor apportioned

*Telephoneline apportioned

♦General improvements apportioned

Hauling sulphurets and back freight on sacks.

Reduction charges and railroad freight on

sulphurets

Total cost per ton

For purpose of comparison, following items

may be transferred from "Sulphurets" to

" ^filling " column :

Labor

Water

Electric light

Miscellaneous supplies —

Assaying

Total

$' cts.

.0082
.0314
.0129
1.3886
.0650
.0013
.2754
.0692
.0103
.0050
.0470
.0080
.0020
.0335
.0085
.0014
.0055
.0201

.0035

.0072
.0008
.0341
.0301
.0017
.0025
.0413
.0045
.0370
.0082
.0272
.0210
.0012
.0100

.$2.2236

cts.

.0084
.0313

.0075
.0653
.0875
.0022

.0031

.0013

^6605
.0003
.0017
.0600
.0007
.0002
.0070
.0020

16034
.0053

.0006
.0665

.0081
.0006

.0004
.0038

v<? cts

3.418
.746
.051

.275
.212

2.203
9.491

$0.3677

.0464
.0100
.0007
.0037
.0028

$16,396

$0.4313

$11,694

♦Because of the deterioration of the machinery, etc., represented by these accounts,
one per cent per month of their cost and repairs is inserted in this report.

§The development is apportioned according to the estimated life of that part of the
mine affected by it.

THE MOTHER LODE REGION — MINING MACHINERY. 39

At the Kennedy Mine, Jackson, Amador County, it may be stated
without particular reference to detail, that the cost of mining, milling,
and all development work, including the new vertical shaft and expense
of conducting chlorination works, is about -to per ton. The details of
the Kennedy cost-sheet are not available for publication, as the com-
pany does not carry their cost-sheet out in all its minutia, being satis-
fied with more general statements of cost and profit, but it may be stated
that the great apparent discrepancy as compared with that of the Wild-
man Company's sheet is due to the extremely unlike conditions obtaining
in these two mines, which are not more than two miles apart. The
Kenned}' vein is much smaller than the great ore-shoots at the Wild-
man, but in the former they are seldom without heavy swelling ground,
which, under the system of mining carried on for years at the Kennedy
and other similar mines, requires constant relief and frequent retim-
bering. This comparison is made merely for the purpose of showing
that comparisons of cost without a complete knowledge of the condi-
tions affecting such cost, are practically meaningless, and are unjust to
the mine managers who are willing to furnish such figures.

It should be remembered in the case of the Wildman Company's
sheet that it includes the years 1896-97-98, but does not include the
years 1899-1900. Within the past two years there has been a very
material advance in the cost of many mining supplies and in mining
machinery. The mine cost-sheet would be affected particularly in the
items of iron, steel, steel rails, hardware, power-drill machinery, wire
ropes, etc., and the mill sheet would show a probable increase in cost of
shoes, dies, screens, quicksilver, hardware, iron, and steel. This increase
in cost of the items enumerated would raise the cost of both mining
and milling, and as a matter of course, would affect all other mines in
proportion to the magnitude of their operations. At those mines
treating the largest quantity of ore per stamp the milling cost would be
lowest, and at those mines hoisting the largest tonnage of ore to the
number of men employed the mining cost would be lowest. Ordinarily,
in the larger mines, the cost of timbering ranges from 30 cents to 50
cents per ton of ore extracted.

MINING MACHINERY.

There is found in the Gold Belt a great diversity of mining machinery
from the crude windlass to magnificent plants costing many thou-'
sands of dollars. When it is determined to purchase a hoisting plant?
it is always advisable to select such machinery as the conditions under
which it is to work, and the object desired to be accomplished, shall
justify. When it is the intention to sink a shaft to great depth, it is

40 CALIFORNIA STATE MINING BUREAU.

the best policy to purchase light machinery at first, and at the depth of
a few hundred feet, when necessary, to exchange this for heavier machin-
ery, but not heavier than seems absolutely necessary to accomplish
the work in hand. Very heavy and expensive hoisting gear is not
advisable for shaft-sinking, nor before the mine has been developed to a
stage indicating the necessity of such a plant for the purpose of hoist-
ing large quantities of rock within a limited time. For instance, it
would scarcely be considered wise to equip a shaft through which it is
expected to raise 400 tons of ore daily, with machinery capable of hand-
ling ten times that amount. Heavy and expensive machinery is only
justifiable when there is sufiicient work for it to perform. There are,
usually, at least two active periods in the life of a mine, which are
distinctly separate. These are, first, the prospecting period; and second,
the productive operating period; though many mines never pass the
first stage.

Among the large new enterprises in the Gold Belt, the operations of
the Mariposa Commercial and Mining Company, on the Mariposa
Estate, are worthy of more than passing notice. These people, with
probably the largest available capital for mining operations in the
State, are prospecting five mines on their property. Everything is being
done in a thorough, workmanlike manner, at the lowest possible cost,
without the exercise of parsimonious economy. The machinery in use
is first class and exactly suited to the work for which it is being used;
that is, prospecting. When the limit of utility of these machines has
been reached, others of heavier design will be substituted, and the
lighter machines employed elsewhere, but no great outlay for plant will
be made until the development of the mines justifies it. In this respect,
at least, the management of these properties is entitled to great credit.

MINE BELL SIGNALS.

It having come to my notice that in some localities the legalized code
of mine bell signals is not in use, it appears important to call attention
to the fact that the California State Legislature adopted a code of mine
bell signals May 1, 1893, which should be adopted by all mines regard-
less of custom or difi'erent practice elsewhere. There is a liability
attached for the non-use of the legal signal code. For the benefit of
California miners the legal signal code is here published.

California Code of Mine Bell Signals.

1 bell, to hoist. See Rule 2.

1 bell, to stop, if in motion.

2 bells, to lower. See Rule 2.

3 bells, man to be hoisted; run slow. See Rule 2.

THE MOTHER LODE REGION — MINE BELL SIGNALS. 41

4 bells, start pump if not running, or stop pump if running.
1 — 3 bells, start or stop air-compressor.

5 bells, send down tools. See Rule 4.

6 bells, send down timbers. See Rule 4.

7 bells, accident; move bucket or cage by verbal orders only.
1 — 4 bells, foreman wanted.

2 — 1 — 1 bells, done hoisting until called.

2 — 1 — 2 bells, done hoisting for the day.

2 — 2 — 2 bells, change buckets from ore to water, or vice versa.

3 — 2 — 1 bells, ready to shoot in the shaft. See Rule 3.

Engineer's signal that he is ready to hoist is to raise the bucket or
cage two feet and lower it again. See Rule 3.

Levels shall be designated and inserted in notice hereinafter men-
tioned. See Rule 5.

For the purpose of enforcing and properly understanding the above
lode of signals, the following rules are hereby established:

Rule 1. In giving signals make strokes on bell at regular intervals.

The bar ( ) must take the same time as for one stroke of the bell,

and no more. If timber, tools, the foreman, bucket, or cage are wanted
to stop at any level in the mine, signal, by number of strokes on the
bell, the number of the level first before giving the signal for timber,
tools, etc. Time between signals to be double bars ( ). Examples:

6 5 would mean to stop at sixth level with tools.

4 1 — 1 — 1 1 would mean stop at fourth level, man on, hoist.

2 1 — 4 would mean stop at second level with foreman.

Rule 2. No person must get off or on the bucket or cage while the
same is in motion. When men are to be hoisted, give the signal for
men. Men must then get on the bucket or cage, then give the signal to
hoist. Bell cord must be in reach of the men on the bucket or cage at
station.

Rule 3. After signal "Ready to shoot in shaft," engineer must give
the signal when he is ready to hoist. Miners must then give the signal
of "Men to be hoisted," then "spit fuse," get into the bucket, and give
the signal to hoist.

Rule 4. All timber, tools, etc., " longer than the depth of the bucket,"
to be hoisted or lowered, must be securely lashed at the upper end to the
cable. Miners must know they will ride up or down the shaft Avithout
catching on rocks or timbers and being thrown out.

Rule 5. The foreman will see that one printed sheet of these signals
and rules for each level and one for the engine-room are attached to a
board not less than twelve inches wide by thirty-six inches long, and

42

CALIFORNIA STATE MINING BUREAU.

securely fasten the board up where signals can be easily read at the
places above stated.

Rule 6. The above signals and rules must be obeyed. Any violation
will be sufficient grounds for discharging the party or parties so doing.
No person, company, corporation, or individual operating any mine
within the State of California shall be responsible for accidents that
may happen to men disobeying the above rules and signals. Said
notice and rules shall be signed by the person or superintendent having
charge of the mine, who shall designate the name of the corporation or
owner of the mine.

Section 3 of the law says: "Any person or company failing to carry
out any of the provisions of this Act shall be responsible for all damages
arising to or incurred by an}'^ person working in said mine during the
time of such failure."

U

THE MOTHER LODE REGION — AMADOR COUNTY. 43

AMADOR COUNTY.

Since the publication of the last report of the State Mining Bureau
(111 the mineral resources of the State, Amador County has taken a
leading place in the movement toward modern mining practice. The
old-time mining methods, in many cases, have been cast aside for more
modern ideas, and it may be said that a new era in mining has only
commenced.

In this county are a number of the deepest mines in the State, as
well as some of the most valuable. Since the early days of mining in
this county, it has been the common belief that the essential feature of
a paying mine in Amador was a contact of greenstone and black slate.
The development of the last few years has proven that this is not abso-
lutely necessary, for some of the best ore-shoots found in this county
are in amphibolite schist, and not associated with any contact. Another
irroneous impression has been that all ore-shoots must necessarily be
found in connection with the black clay slates of the Mariposa beds. To
such an extent has this belief obtained, that it was considered almost use-
less to look elsewhere for paying mines. Investigation of the past season
has demonstrated beyond a doubt that the clay slates of the Mariposa beds
have little bearing upon the value of the ore deposits, and that the
lilack slates found associated with these ore deposits are the result of
an alteration of diabase tuffs, and may usually, if not always, be
readily distinguished from the clay slates. Moreover, the ore deposits
(io not occur for any considerable distance on the contact of these slates
and the massive greenstone, but are independent of them throughout
the county. This subject has been treated at some length in the open-
ing paragraphs of this volume.

Between the southern limits of the town of Jackson and the Mokel-
umne River on the Central Gold Belt, there are at present no mines
which are paying, although active operations are in progress on several
properties included in that section and profitable mines may be
developed. The first mine, coming from the Mokelumne River north-
ward, which may be included in the paying class, is the Z^ila Mine.
In this county, since our last report, a number of old mines have been
reopened, after an idleness of years. The most important of these are
the Oneida, Central Eureka, Lincoln, and Bunker Hill, descriptions of
which will be found in the following pages. The Baliol Mine, near
Sutter Creek, is a new mine which has been extensively equipped and
developed since the publication of the last report.

44 CALIFORNIA STATE MINING BUREAU. jt

Amador Queen No. 1. — This mine is H miles south of Jackson. The
shaft has been sunk to a depth of 1200 feet, with extensive development
at the 160, 300, 500, 1100, and 1200 foot levels. All of the workings of
the mine are in amphibolite schist. Heavy gouges are an important
and characteristic feature of this mine. There is a broad zone of schist?
much foliated and contorted, with the frequent occurrence of seams and
veins of quartz, with occasional high values; galena and free gold are
often observed. Between the 1100 and 1200 foot levels a new shoot of
ore has recently been discovered, which is one of the most promising
observed in the mine. The shaft in this mine has two compartmentsj
and is sunk at a cost of about $30 per foot. Power is furnished by
water under a head of 270 feet, and transmitted by Manila ropes to the

hoist. There are 15 men employed. The Jackson Exploration and

Development Company (Ltd.), owners. James E. Dye of Jackson,
superintendent.

Amador Queen No. 2. — It is 14 miles south of Jackson, and west of
Amador Queen No. 1. The mine is opened through a cross-cut tunnel
run 1000 feet to the vein, where a station has been cut underground and
a double-reel hoisting plant installed. It is run by water power from
a reservoir situated on the hill above, the pipe-line being conducted
through an old shaft. There is a head of 312 feet at the hoist. A three-
compartment winze has been sunk at a uniform angle below the adit?
the vein dipping irregularly. In January last, the shaft was down 730
feet below the tunnel level. The vein occurs in amphibolite schist, and
is chiefly interesting for the amount of arsenical sulphide (mispickel)?
rich in gold, which it contains. This ore is shipped; all work done in
the mine is performed by hand, no machines being in use. The prop-
erty is equipped with a 20-stamp mill; 19 men are employed. The

American Improvement Company of Toledo, Ohio, owners. John R*
Phillips, superintendent.

Anderson {New York) Mine. — It is 3 miles southwest of Jackson,
near Jackson Creek. The mine consists of a number of ore-shoots
or mineralized zones, which occur in a dense aphanitic rock, the
exact character of which has not been determined — probably a diorite-
porphyrite. The ores are found in the crushed portions of this mass,
and consist of impregnations of iron sulphides, free silica, and gold-
The oxidation of these deposits has resulted in the formation of silicious
iron ores carrying free gold. The mine is developed by means of three
tunnels: one a cross-cut, 900 feet in length; the second a cross-cut and
drift, 300 feet; the third a drift, 150 feet. A winze has been sunk in
the latter 70 feet in depth, with a cross-cut 100 feet. In addition to
this there are numerous superficial pits and open cuts along the crop-
pings. There is a building for a 20-stamp mill on the property. In
this at one time a Huntington mill was in use, in which was crushed

THE MOTHER LODE REGION AMADOR COUNTY. 45

2500 tons of this ore, but a mill of this type is not well suited to the
extremely hard, dense ore found in this mine. A ditch carrying 400
inches of water, which at the mine has 300 feet head, is a portion of the
property. W. G. Anderson of Jackson, owner.

Butte Mine. — It is a prospect 5 miles southeast of Jackson, near Jack-
son Butte; is opened by means of a tunnel, and has a 10-stamp mill.
A small force at work. Not visited.

Sjmgnoli Mine. — This is at Clinton, The property was being operated
last spring by the Hobart Gold Mining Company of San Francisco. It
has an old inclined shaft 110 feet in depth, and a new vertical shaft
220 feet in depth. The vein occurs in granite. The mine was not
visited. S. N. Spagnoli of Jackson, owner.

Peerless Mine. — It is 2 miles southwest of Jackson and about 3 miles
south of the Kennedy Mine. An inclined shaft has been sunk at or
near the contact of black clay slates of the Mariposa beds, which occur
on the foot-wall and a diabase tuff on the hanging-wall. ,At the surface
was discovered a small vein of quartz, which prospected well in gold.
There are 10 men emploj'ed. Peerless Mining and Development Com-
pany of Jackson, owners. Henry Osborne of Jackson, superintendent.

Kirkivood Mine. — A new property adjoining the Peerless on the south.
It is in the prospective stage.

Zeila Mine. — It is in the southern limits of the town of Jackson.
Since the last report, the shaft has been sunk from 1160 feet, at which
depth it had remained for some years, to 1506 feet, the lowest level
being opened at 1350 feet. The mine was first worked about forty years
ago, and continuously for the last twenty-one years. The property has
a 40-stamp mill, which was worked steadily for fifteen years, when the
mortars of old style were replaced by modern heavy mortars, provided
with liners, etc. A modification of the Nevada square-set system is
employed in timbering this mine. It is substantially the same as that
used at the Utica Mine, Angels, Calaveras County, but was first intro-
duced in the Zeila Mine.

The Zeila ore-shoot occurs as a broad zone of amphibolite schist and
quartz, 30 to 40 feet wide. The ground is heavy and expensive to hold.
Never a rich mine, it has always, however, paid a small profit. Filling
is necessary in working this mine, and is obtained from the vein and
also from chambers cut in the hanging-wall. The chlorination works at
this mine have been entirely replaced once, and the hearths renewed
several times; a hearth usually lasts about five years. The manager
states that the average expense of mining and milling at the Zeila is
about $3 per ton. In recent years a canvas plant has been added to
handle the tailings from the mill. 115 men are employed. Zeila

46 CALIFORNIA STATE MINING BUREAU.

Mining Company of Jackson, owners. W. F. Detert of Jackson,
superintendent.

The Zeila Mill. — The mill, which is under the direction of B. F. Taylor,
has 40 stamps which weigh 818 pounds, new. The rock is crushed at
the hoist with Blake breakers 9x15 inches. The mill is supplied with
Hendy Challenge feeders. The stamps drop 7^ inches, 87 times a
minute. The screen used is No. 16 brass wire. The discharge is 7-^ to
9 inches high; it is regulated by the introduction of 2-inch differential
chuck-blocks. The capacity is 4 tons daily. There is one inside
plate on the chuck-block. The pulp from the screen falls against a
splash board and drops upon an iron plate (the lip of the mortar), from
which it drops 1 inch to an apron plate 51 inches wide by 30 inches in
length; thence it passes to the sluice plates 16 inches wide by 120 inches
in length. The pulp passes by launders to the vanners. The free gold
constitutes but 35 per cent of the values. The plates are dressed daily
and a clean-up made monthly. Experiments have shown that while
finer crushing will result in saving more free gold, there is a greater loss
of values in sulphides, due to sliming of the ore. The iron shoes and
dies last 100 days, crushing 400 tons of ore. In the Zeila mortars there
is a tendency of the center shoes and dies to wear more rapidly than
those at the end of the mortar. Raw copper plates are used, and it is
rarely the amalgamators have any trouble with copper salts or spots of
any kind on the plates which have never been silvered. This is con-
sidered due to the character of the ore, consisting largely of chlorite
schist with quartz, and containing no rapidly decomposing sulphides.
Mr. Taylor, mill foreman, states that but twice has he ever detected
visible gold in the ore. The sulphides occur to the amount of 2^ per
cent, and have a value of about $100 per ton, which is in strong contrast
with other mines where the average value of the ore is higher than at
the Zeila. At the chlorination works, 7800 pounds of sulphides are
treated daily in three charges of 2600 pounds each. The furnaces are
60 X 11 feet, inside measurements. The Plattner process is employed.

The Zeila Canvas Plant. — The slimes plant is located at the mill.
Owing to the fact that the issue from the mill is near the creek level,
the tailings are elevated by a centrifugal pump to a height of 13^ feet to
a hydraulic sizer or separator; 6^ inches (miner's) of water are required
to run the pump under a head of 150 feet. The daily output of tailings
consists of 32 inches of water and about 150 tons of sand, the output
of a 40-Btamp mill. The hydraulic sizer, which is a modification of the
well-known German spitzkasten, is an invention of Mr. Hambric, who
is in charge of the plant. The accompanying illustration (Fig. 3) will
give an idea of the construction and operation of this device. The pulp
falling into the separator, passes into the first upright pipe in the box,
in which is a smaller pipe with a jet of water under pressure. This

THE MOTHER LODE REGION— AMADOR COUNTY.

47

causes a violent ebullition of the sands, the coarser particles of which
pass out at the bottom, the finer rising from the tube, re-entering the
separator and passing onward to the second pipe, where it undergoes a
similar operation by means of a second hydraulic jet. Here the sands
pass out at the bottom, the slimes rising as before and passing out
through a launder opposite the end at which they enter. The coarse
material from the separator goes to two canvas tables, which accumu-
late about 14 tons of sulphides per month; the grade of these tables is
3 inches in 1 foot, which is the heaviest grade in the plant. Tailings
from these tables go to waste. The finer pulp from the separator goes

The- MAf^5Ric 6EPAf^ATof^
Zeila Suites Pl^nt.

Fig. 3.

to the tables of the main plant, which are in a building 58x140 feet.
The plant consists of 32 main tables, 10 x 12 feet, and 8 auxiliary tables,
for the purpose of taking the overflow when purifying the tables of the
main plant. The grade of these tables is 1^ inches to the foot. The
pulp is divided into four equal portions outside the building, and is
evenly distributed on an inclined plane provided with ribs 3 inches
apart, | inch deep, and ^ inch wide. Along these channels the pulp
flows to the canvas tables. There are eight divisions at the upper end,
which grow less in number as each table is passed, until the last of the
j^eries is reached, where there is but one. At the head of each table is a

Zei la CahVas Plant . olacK-sop.

PisTF{i5urof^

A.

3-
C.
P.
t.

F:
(j.

$,preeider:

Fig. 4.

/r^T^

c/^nVa& Ta3le
Zeiua A^iui

S ' Spreader

Fig. 5.

THE MOTHER LODE REGION — AMADOR COUNTY.

49

distributing device illustrated in the accompanying sketches (Figs. 4
and 5). Throughout the length of the plant clear- water pipes are pro-
vided with faucets opposite each distributer, and between each of two
tables is a hose for washing the tables. At this plant the owners under-
took a series of experiments, of which the chief feature was the
discontinuance of purifying the material concentrated on the canvas, by
washing off the lighter sands before collecting the sulphides. At this
writing (June 10th) the result of this experiment has not been
ascertained. At the foot of the tables are two launders, one for waste,
the other for sulphides collected on the tables. These are kept separate
by means of a movable bridge or apron. The washings from the tables
are re-concentrated on a belt machine, 1000 pounds being reduced to
900 pounds. All pulp from the tables is elevated by means of two

MYDf^AULlC EjECTOF^ or PuMP a+ ZeiLA§LlMES PlANT
JacKson. - CaU
Fig. 6.

hydraulic ejectors, the construction and operation of which is illus-
trated in the sketch (Fig. 6). The pulp passes to a box having the
form of an inverted truncated pyramid, 44 feet square at the top, 18x24
inches at the bottom, and 3^ feet deep. The construction and operation of
this device is shown in Fig. 7, on p. 50. As previously stated, the practice
of purifying at this plant has been discontinued; the experiment has
demonstrated that by sending the concentrates from the tables to the
pointed box effects a saving of from 12 to 15 tons per month, but it also
results in lowering the grade of concentrates. The economic result,
however, has not been determined. No. 8 canvas is employed in this
plant, and lasts one year. Canvas for the complete plant costs $175.
The wear and tear of the plant is stated to be about $25 per month; the

4 — MB

50

CALIFORNIA STATE MINING BUREAU.

-Groome & Hambric of Jackson,

plant cost complete about $6,500.-
owners.

Argonaut Mine. — One mile north of Jackson, adjoining the Kennedy
on the south. The inclined shaft commenced in 1893 has now reached
a depth of 1750 feet, at which point it was stopped by an injunction of
the court, pending a settlement of litigation with the Kennedy Com-
pany. Above this level the mine has produced a large amount of ore,
which has been crushed in a 40-stamp mill with large profit. The
shaft not being sunk on the vein, a series of raises have been driven,
which prove this vein to be continuous from the surface croppings to

^/:

PoirsTED^ox

Z&IL-A C)LI^\E:5 PL>^r«iT
Fig. 7.

the lowest workings. The mine is equipped with a heavy hoisting
plant, capable of working to a depth of 2000 feet. It is run by water,
the power being communicated by means of rope transmission. The
litigation between the Argonaut and Kennedy companies, in which the
former company is plaintiff, is still pending. The geology of the
Argonaut, and of the Kennedy Mine adjoining, will be treated in a
separate paragraph following the description of the Kennedy Mine.

There are 140 men employed. Argonaut Mining Company of San

Francisco, owners. J. B. Francis of Jackson, superintendent.

Argonaut Mill. — The rock is crushed in the breaker at the hoist and
delivered to the mill bins, from which it passes by chutes to Challenge

THE MOTHER LODE REGION — AMADOR COUNTY.

51

feeders. The mill is in charge of Mr. B. Taylor. It has 40 stamps,
which drop 7 inches, from 90 to 95 times per minute. No. 30 brass wire
screen is used. The height of discharge is 8^ inches, which is kept as
nearly uniform as possible by the use of several chuck-blocks. The
capacity of the mill is somewhat variable, owing to changing character-
istics of the ore, but it is about 3.25 tons per stamp daily. The quantity
of water used in the battery also varies with changes in the ore. The
apron plates have a grade of 2 inches to the foot, and the sluices 1|
inches per foot. These are dressed daily; the mill is cleaned up
monthly.

Some experiments of an interesting character were made at this mill.
The pulp was passed through a hydraulic sizer, the coarser material
being sent to a Woodbury bumping-table, and the finer to Union and
Woodbury belt machines. The coarse material treated by the bumper
returned high values, and the fine material from the belts was of medium

iNcuirleo Caw/aS Co/er£d

TA3UEr-

Pl-AK of (^J^OOt^ Ol6TI^I^UTOP^- ^rionaui- Slimes Plan+T^
Fig. 8.

value. This probably represents the two classes of sulphide material
found in this mine; a coarse, high-grade sulphide occurring in the
quartz, and a fine, low-grade sulphide found in the slaty ores.
Another experiment made at this mill was that of re-cleaning all the
concentrates from fifteen machines by passing the concentrates of all
these machines over one Union belt machine, with the result that 12 to
15 per cent of low-grade, silicious material, worth about $10 per ton,
was segregated from the concentrates, which shows that previously a
large quantity of material had been shipped away at a loss, as it con-
tained less value than the cost of transportation and treatment. As the
material thus segregated consists largely of quartz with gold, and a
small amount of iron sulphide, it would seem that a considerable per-
centage might be recovered by grinding the sands in some sort of mill
or pan with quicksilver.

The Argonaut Slimes Plant. — Mr. F. S. Groome has built and
operates a slimes plant below the Argonaut mill — the pulp coming

52 CALIFORNIA STATE MINING BUREAU.

directly from the mill to hydraulic separators, or spitzkasten, and pass-
ing thence to the distributers, the construction of which is illustrated
in the accompanying sketch (Fig. 8). In size, the tables of the main
plant are 8x16 feet. The sized pulp is distributed to three sets of tables,
the coarse going to a set of three tables; the medium, which constitutes
the larger portion of the material, passing to sixteen tables, and the
finest material to a third set of three tables. The fall of the tables
treating the finest material is 1| inches in 12 inches; the grade of the
medium tables is 1^ inches in 12 inches, and that of the coarse 1| inches
in 12 inches; these grades are adjustable. The tables are covered with
No. 8 canvas. Owing to the topography of the ground, it was not neces-
sary to construct these tables in a series of steps lengthwise of the plant,
as in the case of most plants of this character. The canvas is placed
on the long lines of tables in a single piece, reaching the entire length
of the plant, tacked at the edges, and then the entire floor is divided
into a series of tables by tacking down 2-inch strips at regular intervals.
The pulp is run for one hour on the canvas table; it is then shut off,
and clear water turned on for about five minutes, when the sulphides
are removed by means of a hose, usually taking one minute to the table.
It takes one man forty-five minutes to make a complete round, and
about fifteen minutes to look after the outside machines. In this plant,
as at all others, at the foot of the tables is a double launder — one to
carry the waste tailings, the other to carry the concentrates accumu-
lating upon and washed from the tables. The concentrates from the
tables are sent to an agitator, which re-sizes the material, the finer
going to additional tables having a grade of 1^ inches in 12, the coarser
material going to a belt concentrator, the tailings from which are
pumped to an outside table 24 feet in length, the overflow from which
goes to a second set of three tables. The changes in the ore necessitate
slight modifications in the treatment. About 125 tons of material are
treated daily. Of the values that come from the mill, contained in the
tailings, about 35 per cent is actually saved, 65 per cent escaping in the
coarse quartz sand, the gold being evidently bound up in the quartz
grains, which would require a finer crusher to liberate it; but attempts
made heretofore to save this gold at a profit have proven abortive. It
would seem, however, that if this material were crushed in a mill of
proper construction, operated at a minimum cost of power, it might yet
afford a small profit. In the construction of this plant, green redwood
was employed. The foundations were firmly bedded, and the entire
plant constructed with greatest care.

Kennedy Mine. — It is 1 mile north of Jackson, adjoining the Argo-
naut on the north. This property has been, repeatedly described in
former reports of the State Mining Bureau, but as it is one of the most
prominent mines in the State, it merits further mention. The mine has

THE MOTHER LODE REGION — AMADOR COUNTY. 53

been worked continuously since 1885, when work was resumed at a
depth of 750 feet, to its present depth of 2300 feet vertical. About
36,000 tons of ore have been crushed annually for the past fourteen
years, at an approximate cost of $4.50 to $5.00 per ton, which includes
the cost of mining, supplies, insurance, taxes, superintendence, purchase
of property, dead work, and new work. This excessive cost is due largely
to the heavy swelling ground and the cost of keeping the mine open.
Since the last report, the two main shafts have been sunk several hun-
dred feet, and a new vertical shaft has been started on the hillside about
1900 feet east of the old workings. This shaft, in January, had reached
a depth of 915 feet ; at this writing (June 12th), it is over 1800 feet deep.
A cross-cut is being driven from the 2100-foot level of the Kennedy Mine
to connect with the new vertical shaft. The general geological structure
of the mine is referred to in a paragraph below, which also includes that
of the Argonaut Mine adjoining.

The distribution of ore-shoots in the Kennedy-Argonaut vein is of
considerable importance to miners along the Gold Belt, as in these
extensive workings it has been shown that ore-bodies are not absolutely
continuous, either longitudinally or in depth, and that workings
can be driven over the top and along either side of an ore-shoot, and
beneath it, in fact completely surrounding it, in a barren fissure. There
are ore-shoots in the Kennedy Mine that do not approach within sev-
eral hundred feet of the surface. On the 2100-foot level a new shoot
was recently discovered which started on the west or foot wall (diabase),
dipping at an angle of approximately 40 degrees eastward with a trend
to the southward, which is contrary to the usual trend of ore-shoots in
this mine. The main north shoot is wholly distinct and separate from
that on the south, and it is also distinctly different in character. At the
south end of the south shoot, several small veins come in from the hang-
ing-wall side, uniting with the main fissure, and these gradually build
up the large south ore-body.

The principal feature of interest at the Kennedy Mine at present is
the new east shaft. The object of this expensive piece of work is to
make the large bodies of low-grade ore exposed by development in the
mine available at a decreased cost. This shaft has been sunk through
hard greenstone at a rate approaching three feet per day. This was
accomplished by the use of four machine drills, working three shifts.
Arrangements were so made that the timber gang could work uninter-
ruptedly while drilling was in progress below. The machines are set
on two bars disposed near the end of the shaft, and after having been
set in place a full round of holes is put in, from 28 to 35 in number,
without taking down the machines. The holes are drilled from 5 to 6
feet vertically. The manner of pointing these holes is shown in the

54

CALIFORNIA STATE MINING BUREAU.

accompanying diagram (Fig. 9). There is no hand-drilling, all work
of squaring-up, etc., being done with machines. In this shaft 26 men
are employed. The shaft is timbered throughout with 12x12 Oregon
pine; sets 5 feet from center to center near the top, and in the lower
portion 6 feet from center to center. The accompanying illustration
(Fig. 10) shows the relation of the strike of the rocks to the position of
the shaft. (Notice also the strike of rocks in the Oneida and Wildman
shafts in this county — see Figs. 14 and 21.)

An unusual feature in the new Kennedy shaft, not often found in
shafts sunk in hard rock, is the bridge used in timbering; this is illus-
trated in the accompanying sketches (Figs. 11 and 12). It was claimed
by Mr. George W. C. Glass, who was in charge of this work, that this

Sh{E:TCM sho^inS ^3tnr)&r oj^ falacino Machi M&^HouE s

Fig. 9.

method of shaft-timbering greatly expedited matters and was less
expensive than by the ordinary method. This manner of timbering
shafts is not novel, but is usually employed in soft and not in hard
ground; but as the bridges have been carried from top to bottom in
this shaft, and as good headway has been made throughout, it is prob-
able that this method has given entire satisfaction in this instance.

The Kennedy Mill. — This mill contains 40 stamps, and is in charge
of Mr. Webb Smith. The monthly capacity is about 4,000 tons. The
stamps drop 7-J inches 95 times per minute. The height of discharge is
from 8 to 10 inches, three differential chuck-blocks being employed to
keep these as nearly uniform as possible. The grade of the plates is 1^
inches to 12; 24-mesh brass wire screen is used in the battery,

THE MOTHER LODE REGION — AMADOR COUNTY.

55

formerly 30-mesh. The amount of water employed in the battery is
variable, depending on the character of the ore. Cast-iron, chilled,
manganese, chrome, and hammered steel shoes and dies have been used
in this mill. The steel shoes and dies have given the best satisfaction;
the iron shoes last about 50 days, the steel 95 days, the latter crushing
about 340 tons of rock. The plates are dressed daily, and the general
clean-up is made monthly. There are 24 Frue vanners in use. The
sulphides collected on these machines are treated in the chlorination
works at the mine, having a daily capacity of 3^ tons. The average
saving is about 94^ per cent, and the cost is said to be $7 per ton,
paying high salaries to experienced men.

The mortars used in the Kennedy mill were formerly of a wide type
with double discharge, the rear discharge being closed for gold milling.
These have all been replaced by narrow, lined mortars, designed by Mr-

Sketch- si7owi no ^Tf^iK&of f-of{h)-AT\oH across
HCenhepy VertiCt^l ^h-aft

Fig. 10.

Webb Smith, the mill foreman. The mortars are lined throughout, and
have a plate on the feed lip which may be replaced when worn. There

are 150 men employed. Kennedy Mining and Milling Company of

San Francisco, owners. J. F. Parks, superintendent,

Kennedy Slimes- Plant. — All the tailings from the Kennedy mill go to
a slimes plant, one of the first built and successfully operated on the
Gold Belt. The design is that of G. G. Gates of Jackson, who has car-
ried the concentration of slimes to as near perfection as may be wished.
Mr. Gates has also designed an end-shake belt concentrator which does
splendid work on slimes. This machine is used in recleaning the con-
centrates from the canvas tables. The Gates plant is described at length
in Bulletin No. 6, '' California Mill Practices," by E. B. Preston. Since
the publication of that bulletin, Mr. Gates has made no material change
in the design of his plant or method of operating, although the plant
has been entirely rebuilt. In its general features it is similar to that at
the Zeila Mine. G. G. Gates of Jackson, Cal., owner.

56

CALIFORNIA STATE MINING BUREAU.

GEOLOGY OF ARGONAUT-KENNEDY VEIN.

In the Argonaut and Kennedy mines is found a perfect example of
that class of mineral deposit known as, and called, a " true fissure " vein.

TT^

7E><yi^S

1

-V=>o/^

t/cI

TJ-tf-Tc/ cyA/s>

-V-^o/s^

J

'2 CO

't tC)

O

^■^C7/y^/CT

-^U.J=/-Tc^ (7/^3^

■«■ H'i!r-''-iwit:^"^

-^ iy C7/^^

I

By the term " true fissure" is meant a vein or fissure which cuts through
rock formations of either similar or unlike character, Avholly independ-
ent of either the dip or the strike of the rocks which form the walls of

THE M0TIIF:R lode region — AMADOR COUNTY.

57

the vein. Veins of undoubted fissure type do occur, however, which
conform with strike or dip of the wall rocks, and in some instances with
both.

That the Argonaut vein is persistent for thousands of feet in both
strike and dip is abundantly proven in the extensive workings of the
Argonaut and Kennedy mines, the connection of their levels at numer-
ous points showing clearly the identity and continuity of the vein in
these mines.

The geology of the vein is very simple and may be briefly stated. That
geological horizon known as the ''Mariposa Beds" (U. S. Geological
Survey), which consists of deposits of clay slate and altered diabase

y

BlooK

Wcdis

at corrjer of

Fig. 12.

tufi", is found intruded by dike-like masses of diabase. These dikes are
of varying width, and appear to have been thrust in from the north-
ward, where, at a distance of 1000 feet or thereabouts, to the northward
of the Argonaut shaft at the base of Reservoir Hill, the diabase seems to
have almost wholly displaced the slates. To the westward of the most
westerly of these slate strips is found a broad area of typical diabase
(No. 18), mostly massive and granular, extending many thousands of
feet to the northward and southward.

When in their normal position and condition, we find the slates of the
Mariposa beds along the Gold Belt almost universally dipping to the
eastward and striking a few degrees west of north. In the Argonaut

58 CALIFORNIA STATE MINING BUREAU.

Mine local disturbances have resulted in folding, faulting, and crushing
these slates, the degree of foliation and alteration appearing in propor-
tion to the amount of crushing and shearing to which the rock has been
subjected. Whether or not the cleavage of the planes of the slates are
coincident with the planes of sedimentation cannot be determined, nor
is it important. At Sutter Creek it is known that they are not. (For
illustration, see Fig. 20, page 67.)

The diabase has also shared in this alteration from the same causes,
namely, movement and fracture of the rock-masses due to tremendous
compressive stress, resulting in a process of crushing and shearing of
this hard, tough, granular rock, and its consequent alteration to splintery,
schistose, and slaty rocks, with ever}' phase of transition from granular
normal diabase to chloritic schist and slate. (Amphibolite schist, U. S.
G. S.) Diabase when so altered to a slaty condition forms the "gray
slate" of the miners. The slaty structure developed in the tuffs is often
so perfect that in some instances, particularly when found in the vicinity
of the black clay slates where they have become blackened by meta-
morphosing influences, it is extremely difficult and often impossible to
distinguish one from the other by their physical appearance. For a
description of this type of formation see "Schists and Metamorphic
Rocks," by G. H. Williams.

The vein can be followed continuously from its apex in the Argonaut
claim to the lowest level of the mine without break or interruption of
any kind. The apex or upper portion of the Argonaut Mine is wholly
in massive diabase, which is found much decomposed for some distance
on either side of the vein to a depth of several hundred feet, but for
most part retaining its massive structure. (See Fig. 13.) In proxim-
ity to the vein, an alteration to a splintery or schistose condition may
often be observed, and impregnations of pyrite are of frequent occurrence
where such alterations are found. In the hanging-wall diabase near
the surface are found numerous small veins and seams of quartz, some
of which lie nearly parallel with the principal fissure plane, but the
greater number have a westerly dip extending upward from the fissure
into the hanging-wall.

Similar seams and vein-like sheets also occur in the foot-wall diabase,
but usually in less number. These attendant sheets and veins of quartz
are incidental to many veins elsewhere, and very frequently contain
sufficient valuable material to entitle them to be included in the zone
of pay rock together with the main fissure, when the entire zone of
mineralization is, and very properly should be, considered as a single
vein or lode. In making an examination of the vein structure and
wall rocks in a raise extending upward from the 470-foot level to the
adit (Pioneer tunnel) level of the Argonaut Mine, geological conditions
were found to exist which at once determined the fact that the vein

THE MOTHER LODE REGION — AMADOR COUNTY.

59

occupies a " fault fissure," the hanging-wall having moved upward
relatively to the foot-wall, constituting a "thrust" or "reverse" fault.
There may possibly have been also a lateral movement along the fissure
plane to the southward, striations found on the walls of the vein dip-
ping to the northward tending to strengthen this belief. The amount of
displacement as determined by measurement in the raise is about 125

flncient R/\/-(=^

-,.?#=

s/f

^ ^ ' V&f^TlCAL(j0555ECTi0N
(J. ^ " T^roopaut - Kenned/

Vein.

O 3

Fig. 18.

feet. The quartz occurs along this plane in a most persistent manner,
and is rarely absent, even for a short distance. In width the quartz
varies from 1 to 2 inches to upward of 30 feet. Where for a brief
space quartz disappears in the raises above the 470-foot level, the gouge
resulting from attrition caused by movement of these rock planes upon
each other, which always accompanies this vein, clearly indicates the

60

CALIFORNIA STATE MINING BUREAU.

plane of the fissure. In passing through these raises it may be noticed
that where no quartz appears in the fissure on one side of the cutting, it
may usually be found on the opposite side. No more conclusive evidence
of a continuous vein than the fact that it occupies a fault plane could be
desired.

It may be contended that this vein occupies a contact fissure, but the
conditions above described and the abundant evidence found on the
several levels of these mines, indicate clearly that any contact is of
purely local character, and that the fissure is absolutely independent of
it, for the vein does not conform for any considerable distance in either
mine, in either strike or dip, to the contact planes of the black slates
and the diabase, or the schistose and slaty rocks resulting from its
alteration. The dip of the vein varies from a comparatively small
angle at the apex to about 67 degrees from the plane of the horizon in

Sketch showino relation^ op cJTF^lK'E: of Af>jPHI501^TE:a)(;MISr&
-to direc-fion of NeW VEf^TlCAl^HAFT.- One-IDA A^INEr— .

Fig. 14.

the lower levels, and in general at a somewhat less angle than that
of the inclosing rocks.

Oneida Mine. — It is l-j miles north of Jackson, adjoining the
Kennedy on the north. Since the last report, a new vertical shaft has
been sunk in the hanging-wall to a depth of 2050 feet. Ground was
broken for this shaft January 13, 1896, and February 3, 1896, the shaft
had reached a depth of 16 feet, when work was discontinued for the
reason of bad weather. On March 9, 1898, the shaft had reached a
depth of 1550 feet in two years and thirty working days, making a daily
average of two feet. All this work was done by hand, excepting during
a short time when machines were used, but their use was discontinued.
This shaft was laid out to conform with the strike of the formation.
(See Fig. 14.) In this respect it should be compared with the new
vertical shaft of the Kennedy (see Fig. 10), and that of the Wildman at

Oneida Mine, Amador County.

The Central Euiieka Mine, Suttek Cheek, Amadou County.

THE MOTHER LODE REGION — AMADOR COUNTY.

61

Sutter Creek (see Fig. 21). It is claimed that there is considerable
ndvantage gained in sinking the shaft at right angles with the strike of
the formation or diagonally across it. The timbers employed in
timbering this shaft were 12x12 and 14x14 inches. The upper por-
tion, in soft ground, is closely lagged, but the greater part is without
lagging.

Station ^ho Vein - -l^oo f Le/tt-. Orjc'ida IT^ii^e.

Fig. 15.

Three ore-shoots have thus far been discovered in the mine, two of
them near the shaft and the third north of it. The best ore developed
is found on the 1500-foot level, although ore has also been developed
on the 1700 and 1900 foot levels. The old incline shaft which was
sunk by the former operators to a depth of 1350 feet has been cleaned

62

CALIFORNIA STATE MINING BUREAU.

out, a great deal of it being found in a very bad condition. It was
probably one of the most expensive and difficult jobs of opening an old
shaft that has yet been found on the lode. The new vertical shaft and
the old inclined shaft which will be extended downward, will be

g)TATIOH a!'/ c)HAPT.2ooo-ff Level, Oneida 1171176, Amador Co. Cau

FiG. 16.

connected at various levels. The vein crosses the vertical shaft at the
1900-foot station. Here the hanging-wall is diabase and the foot-wall
black tufaceous slate. At the station there is a heavy gouge on the foot-

THE MOTHER LODE REGION AMADOR COUNTY. 63

wall side, and a large vein of fine-looking quartz. In the sump 50 feet
Ix'low the 2000-foot level, and at least 50 feet west of the vein, a thin,
Hat seam of quartz was found in the diabase of the foot-wall, containing
coarse gold. This is an unusual occurrence, or at least one not hereto-
fore observed along the Lode. The method of timbering stations in the
Oneida Mine is shown in the accompanying illustrations. (Figs. 15
and 16.)

A new 60-stamp mill is in course of construction at this writing,
early in June. It will be necessary to elevate the ore by some means,
l>robably an inclined tramway, from the shaft to the ore floor of the mill;
this might have been obviated by sinking the shaft on a ridge a short
distance eastward from the present site of the shaft. A large, expensive
hoisting plant forms a part of the equipment of this mine. Forty-three

men are employed. The Oneida Gold Mining and Milling Company

of West Virginia, owners. C. C. Derby of Jackson, superintendent.

Since writing the above the mill has been completed, and 20 of the
stamps dropped early in September, thus adding another producing
mine to those operating in Amador County.

South Eureka Mine. — This is one mile south of Sutter Creek, adjoin-
ing the Oneida on the north. The north shaft is down 1800 feet, the
south shaft 330 feet, connected with the 600-foot level by a raise. This
vein occurs in black tufaceous slates and greenstone schists. The ore-
shoots trend to the northward and vary greatly in size. The vein is
very much disturbed by faults and flexures, which are difiicult to
understand in the present stage of development of the mine. One per-
plexing peculiarity of this vein is the finding of rich masses of ore in
a large vein of slaty gouge, which have no connection with any con-
tinuous ore-shoot. Recently (spring of 1900), some very good ore has
been discovered in this mine. Another peculiarity of the ore-shoots is
that they are richest in free gold at the north end, while the south end
of the shoots are of much lower grade. It seems characteristic of these
veins that while they are broad, the values are disseminated. In many
of the mines of this county, where the veins exceed 10 or 12 feet in
width, the best portion is found next to the foot-wall. In some cases
from 1 to 10 feet of rock will be found above the average in grade,
while the remaining 15 to 25 feet in thickness will be practically value-
less, consisting principally of white, massive quartz. In this mine the
superintendent has arranged an ingenious device for hauling timbers
into stopes above the level. This consists of two sheaves set above in
the raise, with one sheave at the main gangway. A rope is passed over
these sheaves and a bucket attached at one end. This bucket is hauled
up into the stopes, and a heavy timber attached to the opposite end of
the rope down on the level. When the bucket is filled with ore it acts
as a counterbalance, and the timber can be hauled up with comparative

64 CALIFORNIA STATE MINING BUREAU.

ease. The mine is provided with a 20-stamp mill, run by electricity-
furnished by the Standard Electric Company. The hoist is run by
water power under 180-foot head, the power being transmitted by means
of a wire rope 600 feet long. There are 30 men employed, except when

the mill is running, when there are from 60 to 70. South Eureka

Mining Company, owners. J. F. Parks of Jackson, superintendent.

Central Eureka Mine. — This property adjoins the South Eureka
on the north, half a mile south of the town of Sutter Creek. This
mine, after an idleness of many years, was reopened by a new company
in the fall of 1895. There were several shafts on the property at that
time, the deepest being the south shaft, down 700 feet. Since that time
the shaft has been continued to a depth of 1700 feet and a number of
long levels opened. At about the 1000-foot level, several narrow and
short shoots of high-grade ore were developed. As depth was attained
and levels driven out, these ore-shoots were found to lengthen and
increase in width while maintaining their values, until in the deepest
portion of the mine the several short shoots have united, forming a
single long shoot. At this writing (January, 1900), the Central Eureka
Mine is one of great promise. The vein is the most simple in geological
structure of any extensively developed mine on the Central Lode. It
consists practically of a single fissure cutting in strike and dip the
black tufaceous slates and amphibolite schist which form its walls.
The mine has certain peculiarities which are noticeably persistent.
One of these is the firmness and regularity of the hanging-wall. The
wall is not absolutely straight in strike, but rolls more or less in a
series of long swells. The gouge, which is always found on the foot-
wall side, also has a sinuous course, swinging toward and away from
the hanging-wall. When at some distance from the hanging-wall little
or no ore occurs in the fissure, but upon its approach to the hanging-
wall the long lenticular masses of quartz which constitute these ore-
bodies, begin to form. Another feature of the vein is found in the
increasing mineralization of the rock forming the hanging-wall upon
nearing an ore-shoot. Although at the time of my visit no cross-cuts
had been made in the hanging-wall country from the lower levels of
this mine, there is little doubt that considerable portions of the mineral-
ized zone of the hanging-wall will be found to make payable ore,
although of comparatively low grade. A considerable quantity of the
ore taken from the shoots above described has been milled, returning an
average of about $70 per ton. The hoist is run by water power. A
10-stamp mill has been completed and is in operation. The mill has
an extension for 10 additional stamps. In September the shaft had
reached a depth of 1845 feet, and the vein is from 1 to 12 feet in width
between the 1400 and 1800 levels. A new hoist is being put in, and the
mill, rockbreaker, and exhaust fan are running by electricity. Cen-

The Maiioney ^Iine, Sutter Creek, Amador County.

Timbering in Caving Gkdund, Mahoney Mine, Amador County.

!

THE MOTHER LODE REGION — AMADOR COUNTY.

65

tral Eureka Mining Company, owners. W. R. Thomas of Sutter
Creek, superintendent.

Wildman-Mahoney Mine. — This is at Sutter Creek. The property-
consists of the Wildman, Mahone}' or Hector, and Stewart claims, also
the Waechter ranch to the eastward of these mines on which a new vertical
shaft is being sunk. The development at present is chiefly confined to
the Wildman and Mahoney claims, which join and are operated through
two inclined shafts. The Wildman is 1300 feet . deep, the Mahoney
1000. The 1000-foot level of the Mahoney is equivalent to the 800-foot
level of the Wildman. The ore-bodies of these mines, both great and
small, appear to be confined to a definite zone lying between two reefs
of Mariposa clay slates, although these latter appear not to be directly
associated with the ore-bodies themselves. The zone included between
the clay slates consists principally of amphibolite schist and tufaceous
black slates. In the southern portion of the Wildman Mine the ore
zone is confined to narrow limits, but going northward it broadens, and
in the Mahoney claim the vein splits into two sections, the east

Good ore lying each side, of a 3|{-(^iOu^e "in Wildrrjan VQirje

Fig. 17.

branch going into the Stewart claim and the west into the Lincoln. The
idea seems to prevail that the mines of the Gold Belt of Amador County
are simple fissures, which are easily followed and are regular and per-
sistent. Just the reverse, however, is usually the case, as the ore-bodies
are found disturbed by faults, and often contorted and displaced in a
most puzzling manner. On the 300-foot level of the Mahoney Mine one
vein follows a gouge 4 feet wide, on the hanging-wall of which the ore
continues for a distance of 300 feet; going southward for some dis-
tance the ore loses its value, but undergoes no physical change that is
noteworthy. Noticing that the gouge contained small masses of good
ore, from 20 to 400 pounds in weight. Superintendent Ross cross-cut
into the foot- wall and found good ore in the opposite side. (See sketch,
Fig. 17.) This was the only place known, up to that time, where pay
ore was found in the gouge. The ore found on the foot-wall side of the
zone was 15 feet wide, but its length has not been determined. These
ore-shoots are known to overlap 25 feet at least, and probably much more.
Another instance of irregularity was noticed in the Mahoney Mine 30 feet

5 — MB

66

CALIFOENIA STATE MINmG BUREAU.

above the 900-foot level, where is found what appears to be a displace-
ment of a banded vein 15 feet in width, which, together with the inclosed
slates, is contorted and cut off abruptly, the sheared end abutting against
a solid vein of quartz 20 feet in thickness. (See Fig. 18.) The contin-
uation of this faulted vein has not, as yet, been found above. The slaty
material found underneath the banded vein is also gold-bearing in pay-
ing quantities. A stope on the 900-foot level of the Mahoney follows
a well-defined, persistent wall for a long distance. This stope is 25 feet
in width. A fissure crosses the ore-shoot at an angle of 65 degrees, dip-
ping south. Beyond this was found the above described disturbance.

~AULT on 900 ft Le.VE.L- of -Vrje. Ma-HONEY A\hn E:, Sutter C re elC

Fig. 18.

On the 1000-foot level of this mine, a stope follows what appears to be
the wall above described, with large ore deposits on either side of the
wall. The wall takes a slight flexure to tlie west, and the ore follows
the wall on the foot side, while that previously followed on the hanging-
wall side bears more to the east, and a slate horse separates them. In
the main level, the drift continues south, and a new ore-shoot comes in
from the east or hanging wall. A diamond-drill hole run west, here
passes through 6 feet of slate and cuts 3 feet of quartz, which is suc-
ceeded by 22 feet of slate and 6 feet of ore. This probably represents
the two branches of the divided vein. The diamond-drill hole continues
for a distance of 204 feet, where it cuts a vein of good ore 13 feet

THE MOTHER LODE REGION — AMADOR COUNTY.

67

thick. This may be the downward extension of the ore dipping west-
erly on the level above, though such a thing is far from certain. In the

Sketch of- Vein in Wilomaai Ajinet.

sbow'19^ \ride,per)de,r)ce op Veiip and Contaci^

Fig. 19.

Wildman Mine, on the 800-foot level, is a 24-foot ore-body on the slate
foot-wall. On the 1000-foot level of the Mahoney, what is evidently

Slaty Cleavage: - Pe\/©lop©d by jDres^urein -polded &trata_
OF- /^AF^lPOSA B&DS -AT Su+terCi-eeK'.-V\rriador(2o. C-^u..

HopizoNTAL. Section

Fig. 20.

this same ore-body is developed, but it lies 23 feet east of the slates
(Fig. 19). These irregularities are only a few of those which occur

68

CALIFORNIA STATE MINING BUREAU.

throughout this extensive property, and are simply mentioned to illus-
trate the peculiarities and irregularities of the ore-deposits. A complete
description of the mine, taken by levels, would fill a good-sized volume.
The Wildman-Mahoney Mine labors under great disadvantage in being
obliged to work through the old inclined shafts, that of the Wildman
Mine being particularly bad, and the cause of what would be otherwise
unnecessary expense. The completion of the new Emerson shaft, below
described, will remedy this trouble, and the large bodies of ore, too low-
grade to pay under existing conditions, can then be worked at a profit.
Fig. 20 illustrates the contortion of slates and the subsequent devel-
opment of slaty cleavage in Mariposa beds at Sutter Creek. The sketch
is of an area 20 feet square.

c)KETCM sl^oWi'r^i I^ela-tier^ ojp S-lViKe of foxTTjafio^^h Vi\\drr\ar\

SK|aft

Pig. 21.

The Emerson Shaft. — The new, or Emerson, shaft, as it is called, is
vertical, and is being sunk nearly 1000 feet east of the present Wildman
inclined shaft. It is calculated that it will cut the Wildman vein at a
depth of between 2300 and 2400 feet. It is difficult to give the exact
depth, as through this section the lode flattens more or less in depth.
It is now down over 700 feet. The ground passed through is diabase
and diabase tuff, with some very hard gray slate (altered diabase), an
occasional seam of black slate and stringers of barren quartz. The exca-
vation outside of timbers is 8 x 20 feet, and is made across the stratifi-
cation of the country — that is, the length of the shaft is east and west.
(See Fig. 21.) Timbers used are all selected spruce, 12x14 inches,
framed in the usual Comstock style, with the following exceptions:

First, the wall-plates are placed with the 12-inch side vertical, and
the dividers with the 14-inch side vertical. A dap is cut \ inch deep in
the wall-plate, top and bottom, for the center posts, which leaves 1-^-inch
footing and heading for the posts, as the 14-inch side or end of the
divider comes against wall-plate and posts, thus giving more strength

THE MOTHER LODE REGION — AMADOR COUNTY.

69

to the wall-plate and a better footing for the posts than would be the
case if the divider were of the same width as the wall-plate.

Second, as seen in sketch
of divider (see Fig. 22), a
2-inch filling piece is in-
serted behind each guide,
which gives 4 inches to
work on (in keeping guides
true) in case of a squeeze
in the shaft.

The sketch of section of
shaft (Fig. 23) shows a
small "service cage" in
the pump compartment for
the use of foreman and
pumpmen. It is to be run
open on two sides, to facili-
tate the handling of long
lengths of pipe. All of the
pipes are set on the side of
the shaft opposite this cage.
The ladders are each 15

Section opQuioesA'^ Dividef^

xx^c lauvxcis ttic cauii -L^ 3|^o^,pA Fi H 1 no Piece- WildmanShafh.
feet long, inclined over each •*

other, there being a landing
at the end of each ladder,
from center to center of

Fig. 22.

The shaft sets are 4 feet apart, or 5 feet
wall-plates. The skip compartments are

Af^F{ANGe./v)ENT OP- TTfvJQErRS - WlLD/V)A/s| Sh/\F-T.

Fig. 23.

4^ X 4^ feet, and the pump and ladder compartments 4| x 5 feet. The
wall-plates and ends of dividers are so framed that the dividers are
driven up into place instead of down, which prevents their being
knocked out by blasts.

70

CALIFORNIA STATE MINING BUREAU.

It is the intention to use skips that will carry 3 tons of ore at a load,
making total weight of load (including cable and skip), starting at a
depth of 2500 feet, about 6 tons. Foundations of stone and cement for
permanent headgear have been built from bedrock to the level of the
collar of the shaft. The temporary hoist and gallows frame now in use

NlW a)T/Lt OP SdR&fcN Ff^AME-
a+-

WlLDMAN MlJ-L
without ii^side Plates.

Fig. 24.

at this shaft is so constructed and arranged that the permanent steel
head frame can be erected over the shaft without interfering with the
progress of work. The design of the proposed steel headgear is by E
Chodsko, of San Francisco. If erected this year it will be the first of its
kind in California.

THE MOTHER LODE REGION — AMADOR COUNTY.

71

The Wildman Mill. — The mills of the Wildman Company are operated
with as great care as any in the State, and merit a detailed description.
There are two mills, each of 40 stamps. In the Wildman mill the
stamps weigh 850 pounds; these drop from 7 to 9 inches 96 times per
minute; the guides are of iron; the height of discharge is 7^ inches,
regulated by chuck-blocks, having a difference of 4 to 2 inches in height.
A No. 2 punched tin screen is used. The capacity of the mill had been
about 145 tons per day under the above conditions, but the height of
discharge has been lowered not to exceed 6 inches for the purpose of
experimentation. This will have a tendency to increase the capacity of
the mill. The outside plates have a grade of 1^ inches to the foot.

Iron bar.

DE.TAIU

Sectional Plate
ON Chuci^^uoci\-

(gracKfet.

Old Style ^(REEN Pf^A/^Er
WildnjaoAJill.

Sorean

Detaiu.
/fanner of Wed^iQ" Sc(\een i"^ N]ain FT^Af^fr

Fig. 25.

There are 14 Frue vanners and 2 Triumph concentrators in use. The
ore contains about 1^^ per cent sulphurets, which are shipped to Selby's.
They formerly used 11x48 inch No. 24 Russian iron and cold rolled
steel screens, diagonal slot. Of these the steel screens proved the most
durable. They now use a No. 2 punched tin screen having 225 holes to
the square inch. These apertures have a slightly greater diameter than
the slot of the No. 24 screen. Formerly the screen was secured flush
with the outside of the frame, which was provided with an inside plate.
The screen frames are now arranged as shown in the accompanying
drawing (Fig. 24). The former method is shown in Fig. 25.

The Hector or Mahoney Mill. — In this mill there are 40 stamps, which
weigh 950 pounds. The height of the drop is from 7 to 9 inches 96 times

72 CALIFORNIA STATE MINING BUREAU.

a minute. The height of discharge was formerly 6^ inches, but is now
from 3^ to 4 inches, being adjusted by diflferential chuck-blocks. The
Globe Iron Works guides are in use. A No. 2 punched tin screen is
used, the capacity being 146 tons per day. Chrome-steel shoes and dies
having 8^ inches diameter are used. There are 16 Frue vanners in
the mill which concentrate the sulphides, these constituting ly^o per
cent of the rock. In the Hector mill the pulp falls from the batteries
onto a 4-inch plate and drops to a second plate pitching backward, falling
on the lip of the mortar below, in front of which is a 5-inch plate with
a f-inch drop to the first apron plate 28 inches wide. The inside
plates have been taken from the mortars and every effort made to in-
crease the capacity of the mill, while giving the most careful attention
to outside amalgamation. Below the first apron plate, the pulp falls
into a trough 3 inches wide and 4^ inches deep, discharging through ten
1-inch auger holes, then to a 3-inch board and onto plates 24 inches
square, arranged in double parallel series. The pulp passes by two
drops to two other sets of plates, at the foot of which is a mercury trap.
Below the trap are sluice plates with three drops of 2 inches each.
These plates are 12 feet long, at the lower end of which a second trap is
arranged, from which the pulp goes to the vanners. 165 men are em-
ployed in the mines and mills. The Wildman Gold Mining Company,

owners. John Ross, Jr., of Sutter Creek, superintendent.

Lincoln Mine. — It is at Sutter Creek. This property was worked in
early days, a shaft being sunk 807 feet. To a depth of 350 feet, or
thereabouts, it is said that the mine paid handsomely. At that depth
a fault intersected the vein and all trace of it was lost. The present
company re-opened the mine in the latter part of 1898. The old shaft
was repaired, the workings cleaned out, and sinking resumed in Febru-
ary, 1899. The shaft is now 1260 feet in depth. On the 500-foot level
a drift has been extended several hundred feet, and a cross-cut run both
east and west about 200 feet north of the shaft. That portion east of
the main gangway is in tufaceous slate and diabase, and that to the
westward passes through the black tufaceous slates, and then through a
broad zone of hard, amphibolite schist, to the black clay slates of the
Mariposa beds 315 feet west of the gangway. In this cross-cut are
exposed three ore veins, one of which has been drifted for a distance of
168 feet. This vein is 110 feet west of the gangway. A second vein is
encountered 135 feet farther west. This vein is from 6 to 20 feet wide,
and carries a satisfactory grade of pay rock consisting of quartz and
amphibolite schist with disseminated auriferous iron sulphide and free
gold. It has been developed by a drift 200 feet long. The third vein
lies about 70 feet to the westward of the last-mentioned vein, near the
contact of the amphibolite schist and the clay slate of the Mariposa
beds. It has not been developed as yet. As there appeared to be

Lincoln Mine. Sutter Creek, Amador County.

y

The Bunker Hii.i, Mink, Amadoi; Chuntv,

1

THE MOTHER LODE REGION — AMADOR COUNTY.

73

-ome doubt as to what had occurred at the 350-foot level, when the
mine was formerly operated, a careful examination of an old abandoned
level extending from the shaft at 400 feet from the surface was made by
Superintendent Voorheis and the writer. An investigation at this
point discovered the fact that a fault fissure had dislocated the vein.

' I ■ J « , J

JJJ^^

Jj'j J

u ' i ^

Cro55 Section- Lincoln /^^ine: . gutter CreeK;-T^+n?ai(9 shafh-_

Fig. 26.

The fault strikes nearly parallel with the vein, dipping to the eastward
at an angle of about 58 degrees, and appears as a zone of fracture and
movement 4 to 6 feet in width. To the eastward of this fault plane the
schists and slates and the vein itself all have an easterly dip. Under-
neath the fault plane, however, the entire country — schists, greenstones,

74 CALIFORNIA STATE MINING BUREAU.

slates, and veins — dips strongly to the westward. In the west cross-cut
north of the shaft on the 500-foot level, and in a west cross-cut south of
the shaft on the same level, this condition is clearly in evidence. A
cross-cut run westerly from the shaft at the 650-foot level shows the
formation to be still pitching to the westward, though in a cross-cut at
the 800-foot level it is standing nearly vertical, and on the 1200-foot
level the formation has assumed nearly its normal easterly dip in the
neighborhood of the shaft. On this level, at the face of the cross-cut
275 feet west of the shaft, it has a slight westerly dip. These workings
show that the entire formation lying to the westward of the fault plane
has been contorted from its normal position, having a westerly instead
of an easterly dip, although as depth is attained the formations appear
to assume their normal positions. The sketch (Fig. 26) illustrates the
structural features of the Lincoln Mine. All the evidence obtainable
leads to the belief that the rich vein worked from the surface slipped
downward along the fault plane, and that its further extension down-
ward must be sought in the country lying to the westward of the shaft,
and it is the belief of the writer that the cross-cuts on the 500-foot level
have intersected the vein which was dislocated by the fault at the 350-
foot level.

The mine is well equipped with steam hoist, air-compressors, machine
shop, and other accessories, but has as yet no mill.

In recovering the old Lincoln shaft, the settling of the ground had
forced the shaft out of line, which necessitated the removal of a large
amount of ground from the hanging-wall side of the shaft. To keep it
in alignment this space was timbered in square sets, the number of the
sets varying with the distance from the shaft to the solid ground. This
has not been found to give any trouble.

In swelling ground, such as is found in this mine and many others in
this county, experience has demonstrated the advisability of cutting
large stations and placing sets outside of the main station sets ; lagging
openly — leaving spaces 8 to 10 inches between the lagging, which
preferably, should be light. These light lagging, under pressure from
the swelling ground or from a squeeze, will bend and eventually break
thus giving sufficient warning before material damage results to the
main members of the set. The open spaces are useful in cutting out
and removing the swelling ground, and the lagging may be removed if
necessary, but the main timbers will only occasionally require resetting

or renewing. There are 24 men employed. The Lincoln Gold Mine

Development Company of San Francisco, owners. E. C. Voorheis,
superintendent.

Mutual Mine. — On the summit of the ridge between Sutter Creek and
Amador City. A vertical shaft has been sunk on this property to a
depth of 400 feet (March 1, 1900). Cross-cuts are being run to prospect

THE MOTHER LODE REGION — AMADOR COUNTY. 75

two veins, one of which lies in the black slate on the hanging-wall side
of the shaft, and the other in greenstone schist on the foot-wall side.
The hanging-wall vein has been reached and good ore found in a drift
on the vein. In some surface workings very good ore was taken from
the foot-wall vein. The mine has a substantial steam hoist, and is
" otherwise well equipped for prospecting. There are 15 men employed.

Mutual Mining Company of San Francisco, owners. S. R. Porter

of Sutter Creek, superintendent.

Baliol Mine. — This is 1 mile east of Sutter Creek, and comprises a
number of claims on patented agricultural lands, and covers a series of
veins in amphibolite schist. An inclined shaft has been sunk to a depth
of 750 feet, with levels at 200, 300, 500, and 700 feet and stations at 400
and 600 feet. In a cross-cut run easterly from the shaft, a distance of
380 feet, four of the veins have been intersected ; No. 1, the foot-wall
vein, is cut at a distance of 110 feet from the shaft, and is about 12
feet wide ; No. 2, 39 feet farther east, is from 7 to 17 feet wide ; No. 3, 35
feet eastward, is 60 feet wide; and No. 4, 74 feet beyond the last, is 6
feet wide. Since February, 1900, a cross-cut east from the 500 station has
discovered higher grade rock than any found in the veins above men-
tioned. All stoping is done by means of machine drills. The diamond
drill has been used with good results in this property, bore holes driven
to the eastward having cut good-sized bodies of ore some distance from
the main development of the mine. A large amount of ore has been
stoped from three large open cuts, all showing a similar character of ore.
The large veins resemble, somewhat, those of the Utica-Stickle mines of
Angels. The foot-wall is diabase tuff, slightly schistose. The hanging-
wall is also of this character, but farther east are intrusions of granitic
rock. A granular-dike rock of light-gray color, much silicified, and
containing about 2^ per cent sulphurets, constitutes, together with vein-
like masses of quartz, the principal ore-shoots in this mine. Occasionally
copper sulphide and arsenical sulphide ores are found. The property is
equipped with a 40-stamp mill, the stamps weighing 1100 pounds, drop-
ping 5 inches 102 times a minute. No. 35 mesh punched tin screens are
used, the discharge being from 4^ to 5 inches high. The capacity of the
mill is 4^ tons per stamp. Chrome-steel shoes and cast-iron dies are in
use; one shoe will outlast three dies, the life of the shoe being 112 days.
Risdon vanners are used for concentration. There is no canvas plant.
The plates are 60 inches by 24 feet, with a l|-inch drop. The apron plates
are on carriages, and may be rolled away from the front of the battery
when necessary to clean up. The plates are dressed as often as neces-
sary— usually twice in 24 hours. The proportion of free gold is variable,
constituting from 40 to 70 per cent of the values. The sulphurets are
shipped to Selby's. The mill and air-compressor are run by water power.
The hoist is operated by air, the compressor being located at the mill.

76 CALIFORNIA STATE MINING BUREAU.

It has an automatic hydraulic governor, made at the Knight foundry of
Sutter Creek. This maintains a pressure at 80 to 100 pounds. The
compressor is driven by a water-wheel under 452 feet head. There are

100 men employed. The Western Gold Mining Company, owners.

W. H. Storms of Sutter Creek, superintendent.

Potazuba Mine. — It is situated 1-| miles east of Sutter Creek, adjoining
the Baliol on the west. The shaft has been sunk to a depth of 500 feet
on the vein, with a sump 40 feet, by means of a small steam hoist.
Levels have been run at 100, 200, and 350 feet; the shaft and levels are
on the vein, which varies from a few inches to 12 feet in thickness. The
foot-wall portion of the ledge has proven very rich. At the Zeila, Wild-
man, and Baliol mills were made several runs of the rock from this
foot-wall strip, which have produced about $15,000, averaging about $25
per ton, some of the ore running as high as $100 per ton. The hanging-
wall portion of the vein is low grade. The mine is in the hands of a
local company, which has spent $40,000 in its development. Heavier
machinery will be required to sink to greater depth. At present the
mine is idle from lack of funds to properly equip it, although it is

expected to resume operations some time this year. The Potazuba

Company of Sutter Creek, owners. W. J. McGee of Sutter Creek, sec-
retary.

Treadwell & Guliana Mine. — This is 8 miles east of the town of
Sutter Creek. There are two veins in the property, on one of which, the
Treadwell, there are two tunnels, one 700 feet, the other 300 feet in
length; besides which there are numerous superficial cuts. The vein is
from 1 foot to 12 feet wide, and has produced some high-grade ore. The
Guliana vein was discovered in the bed of Sutter Creek, where it is 3
feet in width, showing free gold. There is a 30-foot shaft and a short
tunnel on this vein. The mine is idle. The mill which was formerly
on the property is dismantled. The mill contained 6 stamps, and was.
operated by water under 150-foot head with a 10-inch pipe-line. This
did not apparently afford sufficient power to run the mill, and it was
consequently shut down. Several years later, it is said, it was discov-
ered that in some manner a piece of scantling had gotten into the pipe-
line, descended by suction to the nozzle, clogging it, and reducing the

power to the extent described. M. D. Nixon et al. of Sutter Creek,

owners.

Free American Mine. — This is 6 miles east of Sutter Creek, on a
small vein of high-grade rock in Calaveras formation. In one place it
is stated that the vein is 6 feet wide, and that the rock will run $25 per
ton, and at the bottom of the shaft the vein is 8 feet wide in good mill-
ing ore. The shaft has been sunk to a depth of 110 feet near Sutter
Creek, and a drift extended out under the creek along the vein, with the

THE MOTHER LODE REGION — AMADOR COUNTY. 77

result that the mine was floocled, the surface water probably coming
directly from the creek. The property was provided with both water
and steam hoist, a jackhead pump and a steam pump, both of which
were operated as vigorously as the power would permit, in addition to
bailing with the skip at the same time; but this combination failing to
lower the water in the shaft, operations had to be abandoned. A light

10-stamp mill forms a portion of the equipment of the mine. Wilfred

Dennis of Sutter Creek, owner.

South Spring Hill Mine. — This property adjoins the Keystone on
the south, and is in many respects similar to it geologically. After an
idleness of about seven years, operations were resumed in June last, and
at this writing (June 10th) the mill is about ready to start. It is said
that good ore is being found at the north end of the mine. — South
Spring Hill Mining Company, owners. John R. Tregloan of Amador
City, superintendent.

South Keystone Consolidated Mine. — This is half a mile south of
Amador City, adjoining the South Spring Hill. It is in the prosiDective
stage. — J. A. Mclntyre of Amador City, owner.

Keystone Mine. — This is at Amador City, and is one of the most
extensively developed mines in the State. There are probably not less
than 10 miles of underground workings in this famous old mine; but all
work at present is confined to points above the 1000-foot level, although
the shaft is 1575 feet in depth. The formation at the Keystone Mine
consists of diabase tuff, tufaceous slates, and the clay slates of the
Mariposa beds, the latter lying west of the principal veins. To the west
of these clay slates, massive diabase is again found. The principal veins,
however, are those occurring in the tufaceous slates. The main vein occurs
along a fault plane, which has a variable dip from 35 to 65 degrees to
the eastward and extending more than 2000 feet in a remarkably straight
course. On the hanging-wall side of this fault plane occurs immense
masses of diabase material and quartz, which in places is more than
100 feet in width. Considerable portions of this constitute payable ore,
although there are large quantities which it will not pay to mine. This
great, massive vein forms the hanging-wall of a banded slaty vein,
which has produced a large amount of pay rock south of the main shaft.
Between the 400 and 600 levels on this vein an immense stope covering
a superficial area of 20,000 square feet has been cut, the vein in places
being 25 feet in width. There are few timbers and but one or two
pillars in this great stope, which has been open for years, which indi-
cates how well this ground stands without artificial support. This is
probably the largest open stope on the Gold Belt. This was being filled
as rapidly as possible during my visit, in order that the large amount
of ore known to lie in the overhanging (so called) wall may be mined

78 CALIFORNIA STATE MINING BUREAU.

without danger. On the hanging-wall side of these veins is a green-
stone formation several hundred feet in width, through which a cross-
cut has been run from a neighboring gulch. Sections cut for microscopic
study (Nos. 10 and 11) prove this rock to be diabase tuff. Lying
between this massive tuff and a broad zone of black tufaceous slate is a
dike of crystalline, granular diabase of normal type. The tufaceous
slates are from 400 to 600 feet in width, and constitute the zone of fissur-
ing in which are found the several veins and ore-shoots of the Keystone
Mine. The veins all intersect the inclosing rocks in strike and dip, the
dip of the slates always being steeper than that of the veins, excepting
where disturbed locally. The region of greatest disturbance is found in
the western portion of this slate zone. The great quartz vein lying in
the hanging-wall side of this zone is from 1 foot to more than 100 feet
in width when measured at right angles to its dip. It is made up of
great lenticular masses of quartz and brecciated quartz and diabase,
having interior fissures or planes running nearly parallel with the
strike of the vein. These are usually referred to as walls. Some of
these masses are built up by the splicing of the lenses. On the 800-
foot level, and a few feet distant in the east wall of this vein, is an
interesting though small vein in a reef of pyritic, black tufaceous slate.
Through the center of this reef is found a small irregular vein of quartz,
with a small gouge and with numerous flat branching seams. The
occurrence of arsenical iron sulphides is a marked and persistent
feature of this little vein, but a more interesting feature is the occur-
rence of pockets of gold, ranging in value from a few cents to over a
hundred thousand dollars. The latter was obtained between the 800
and 900 levels. Within the past year, Mr. W. A. Prichard, the superin-
tendent, has discovered a number of good-sized gold pockets in this
vein. On the 800-foot level a dike of diabase intervenes between the
great massive vein and the pocket vein above described, while on the 900-
foot level, about 200 feet farther north, the diabase and reef of pyritic
slate are passed through before the great vein is encountered. Arsenical
sulphide was also discovered on the 900-foot level, in this vicinity.
Although no pockets have been found on the 900-foot level, or below it,
the indications are that the pocket vein is older than the great vein
cutting across it, and that the pocket shoot may be found from the 900-
foot level downward in the foot-wall of the great vein. In the large
vein are found the widest stopes in the mine. West of this are two
veins, separated from each other and the great vein by varying widths
of tufaceous slates. These veins were also extensively worked in former
years.

A careful and detailed study of the Keystone Mine would undoubtedly
furnish material for a book much larger than the volume in which this
description is found. There are 90 men employed in the mine and mill.

THE MOTHER LODE REGION — AMADOR COUNTY.

79

Keystone Consolidated Mining Company of San Francisco, owners.
W. A. Prichard of Amador City, superintendent.

Keystone Mill. — The mill consists of 40 stamps, and two Griffin mills.
The latter were formerly used in crushing the fine material from the
mine, but are at present not in use. The mill is run by water power,
and the hoist by steam. The mill is under the direction of C. E. Bunker.
The stamps when new weigh 725 pounds. Prior to March 10, 1890, they
were dropped 90 times a minute. A Pelton wheel was put in the mill
at this time to run the concentrators independently, and the stamps
were speeded to about 100 drops a minute, the height of the drop being
from 7 to 7i inches, and the discharge 7i inches high. Nos. 6 and 7

CORRUQATED PlATEzT

Chuck Block of- Keystone Mi lu,

aMd

Device: for regulating ^eio^-h of
discl^ar^e.

M o /=? TA f^

Fig. 27.

angle-slot steel screens are used. The chuck-blocks are arranged so as
to drop half an inch at a time. A variety of shoes and dies have been
tried here, including cast-iron, manganese, chrome, and hammered steel.
The capacity of the mill per stamp is 2^ to 3 tons per daj-, varying
somewhat with the character of the ore. This low capacity is probably
attributable to the light-weight stamps. The inside plate is curved,
and 6 inches in width. The apron plates are 52 inches wide and 4 feet
long, having a grade Q>i\\ inches in 12. Below this the plates are nar-
rowed to 48 inches for a length of 10 feet, below which they are further
narrowed to 30 inches and 24 inches long, with a trap at the bottom.

Since February 1, 1900, numerous changes have been made in this
mill. On an experimental battery, the chuck-block has been changed

80 CALIFORNIA STATE MINING BUREAU.

SO as to reduce the width of the mortar 2 inches, by placing the screen
flush with the main frame. The stamps have been speeded to 100 drops
a minute; the discharge has been lowered, and closer attention is being
given to outside amalgamation. The apron plate has been widened to
60 inches for a length of 16 feet, and the grade of these plates has been
reduced to If inches per foot. No water is added outside the batteries,
as in all the others, and the inside-battery water has been reduced to
the lowest possible amount. The lowering of the discharge would prob-
ably have increased the capacity of the mill, but the decrease in the
amount of battery water has a tendency to retard discharge. The
capacity of this battery is about the same as that of the other batteries,
but as a result of these changes, the tailings have shown a marked
decrease in value, and it is the intention to adapt the entire mill to these
changes. A new chuck-block with corrugated copper plate (see Fig. 27)
has been introduced in this mill.

Bunker Hill Mine. — It is 1^ miles north of Amador City. This prop-
erty is a consolidation of the Bunker Hill and May Flower. On it is a
shaft in the May Flower 350 feet in depth. The old shaft of the
Bunker Hill was sunk to a depth of 800 feet; it had been closed for a
number of years when it was re-opened in the latter part of 1899. The
upper portion of the shaft was badly caved, which required a great deal
of work to recover. A cross-cut tunnel was driven some years since
near the base of the hill to connect with the old May Flower shaft at a
station, and a branch driven beyond in the direction of the Bunker
Hill. This latter has been continued to the Bunker Hill vein, it being
the intention to drain the mine of surface water throvigh this tunnel.
There is also a shaft 400 feet deep on the south end of the property.
The hanging-wall of the vein is a fine-grained grayish rock (No. 16),
in places carrying considerable finely disseminated iron sulphide; this
rock is diabase tuff, greatly altered. The slates found in the foot-wall
are the result of alteration of tufaceous diabase, and bear the character-
istic pitted marks which distinguish this class of slates in Amador.

In its early history, the Bunker Hill is credited with a production of
about $1,000,000 down to the 700-foot level. The shoots have a southerly
trend. The mine is equipped with a substantial steam hoist, but as yet

has no mill. 20 men are employed. The Bunker Hill Consolidated

Mining Company, owners. C. R. Downs of Sutter Creek, superintendent.

Fremont Mine. — This property, 1^ miles north of Amador City, com-
prises the Fremont, Gover, and Loyal Lode, 4200 feet on the lode. The
principal work on this propertj'^ is on the Gover Mine, the main shaft
of which is down 1500 feet on an incline, being 1050 feet vertical. There
are ten levels, and in the lower levels of the mine there are developed
large masses of low-grade quartz. In the earl}'- part of the present year,
a new shaft was started on the Fremont claim. This is an inclined

THE MOTHER LODE REGION — AMADOR COUNTY. 81

shaft, sunk at an angle of 51 degrees below the horizon. It is started
in the hanging-wall of the vein, which it is calculated to intersect in
depth. The close proximity of the old flooded works of the Gover will
probably render the sinking of this new shaft a difficult if not dangerous
operation; at least such has been the experience of others who have

attempted to sink new shafts in the vicinity of old flooded workings.

Gover Consolidated Gold Mining Company, 10 Market street, San Fran-
cisco, owners. C. E. Purington of Amador City, superintendent.

Phoenix Reduction Works (Chlorination). — This is at Dry town, and
consists of a single reverberatory furnace, with all the essential vats,
etc., for a complete plant of the Plattner type. (No barrel chlorination
is practiced in this State.) The Dry town plant has a capacity of 3 tons
daily, and treats custom ores only. There are 5 men employed. E. S.
Barney of Drytown, owner and superintendent.

In the chlorination process as practiced in Amador County, the
auniferous sulphides which are derived from the ores by the various
methods of concentration, are charged in reverberatory furnaces usually
containing about 10 per cent moisture. The charge is moved forward on
the hearth every eight hours, and a new charge introduced. These
furnaces are from 60 to 65 feet in length and from 11 to 14 feet wide.
Pine wood is used for fuel, the quantity required per ton of sulphides
being one fourth to one third of a cord. The charge of ore ranges from
2000 to 2500 pounds. Three charges are introduced every twenty-four
hours. A ''dead roast" is absolutely essential to a complete and suc-
cessful extraction of the gold. Dampers are provided in the stacks,
which are manipulated with the greatest care.

When the sulphides take fire, and following the volatilization of the
arsenic, should any be present, but w^hile sulphur still remains, salt is
added. After the pulp has been withdrawn, it is allowed to cool and is
dampened, the proper amount of moisture being determined by com-
pressing a quantity in the hand. If it fails to crumble, it contains too
much moisture; if it crumbles rapidly, the amount of moisture is
insufficient; but when the compressed ball slowly disintegrates, it' is
considered to have the proper amount of moisture. The pulp is charged
in vats by being shaken over screens, the charge being from 4 to 6 tons.

Chlorine gas is generated in lead-lined vessels, the following materials
being employed: salt, 50 to 60 pounds; manganese dioxide, 30 to 40
pounds; sulphuric acid, added as long as gas is generated. When the
vats have been charged with pulp, the gas is turned in, passing upward
through the false bottom of the vat, penetrating the charge, and event-
ually reaching the surface. Tanks are gassed until it shows near the
surface of the charge, which usually occurs in from three to five hours,
when the cover is luted on. The gas is shut off when it appears on the

6— MB

82 CALIFORNIA STATE MINING BUREAU.

surface. This period is determined by holding a l)ottle of ammonia near
a small vent in the cover. Upon the appearance of the chlorine gas
through this vent, a dense cloud of chloride of ammonium at once forms-
Water is introduced through a hole in the cover, falling on a burlap
sack. It is a common practice to allow the water to stand from one to
two hours, when it is turned into the precipitating tank. The water is
permitted to run until the iron sulphate solution fails to show the
presence of gold, samples being taken from the vat. If the assay of
samples shows that high values remain in the pulp, it must be removed
from the vats and *'regassed," The leaching vats are provided with a
double floor; these are made with slats 14 inches in width placed 18
inches apart. Upon these and at right angles to the first are laid 1-inch
boards 4 inches wide, covering the bottom; these are 2 inches apart.
Upon this floor is placed a quantity of quartz gravel (clean creek
gravel being preferred), usually laid in courses, to a depth of about 6
inches. Upon this filter are laid the shoveling boards, 4 inches wide
and 1 inch in thickness, they being separated by a space of 1 inch.
These spaces are filled in with fine gravel which will pass a No. 12
screen. A solution of iron sulphate is employed to precipitate the gold
from the chloride solution. The precipitate is washed and smelted with
borax.

Centennial Mine. — This property is 1-j miles northeast of Drytown.
An inclined shaft has been sunk 565 feet, and sinking was in progress
in April last. This shaft, started on the vein, passes into the foot-wall,
and cross-cuts are run to the vein at the 150, 250, and 850 levels. On
the first the vein was found from 8 to 8 feet wide; on the second, 18
feet; and on the third, about 2 feet. The shaft will be continued to a
depth of 1000 feet. The formation is greenstone schist (after diorite).

Centennial Mining Company, owners. L. A. Gross of Drytown,

superintendent.

The formation from the neighborhood of Drytown to Plymouth is
largely amphibolite schist and diorite, tufaceous slates, and Mariposa
clay slates. Many veins of quartz occur, both large and small, and
also zones of amphibolite schist with quartz. There are many prospect
holes of various depths throughout the region, but with the exception of
those here mentioned, no operating mines.

Plymouth Consolidated Mine. — This property is at Plymouth, and has ^"
been idle for many years, but within the past year the old dumps have
been worked with profit in Huntington mills. These dumps were
estimated to contain over 250,000 tons of rock. The reduction plant
consists of four 5-foot Huntington mills with hydraulic sizers, Wilfley
and Woodbury concentrators, and canvas plant. Power is furnished by
water from the Hayward ditch under a head of 572 feet. The dumps

THE MOTHER I,ODE REGION — AMADOR COUNTY. 83

were moved at very low cost by cutting in at their base and running an
open cut directly into the end of the pile of rock. When a face of suf-
ficient size had been exposed, a movable chute was placed against the
face, by means of which all the rock above the level of the chute was
easily delivered to cars beneath the chute. The rock was trammed to
the mill, hoisted in the car by means of a hydraulic elevator, dumped
onto the grizzlies, from which it passed to the rockbreakers, falling
into a bin. From the bin, the rock was delivered to automatic feeders,
thence to the mills.

Diagonal slot screens from 12 to 20 mesh are in use. From the mill
the pulp flows to the sizers, from which the coarse material goes to the
concentrating tables and the slimes to the canvas plant. The principal
source of value in the dumps is in the sulphurets, which average about
If per cent. The free gold is caught with the concentrates, which are
shipped to Selby's. The following statement is made by the manage-
ment relative to the cost of working:

Thirty Days' Milling, 3750 Tons.

Cost of delivering rock to mill $375 00

Milling, including canvas plant 510 00

Water 240 00

General expense 110 00

Total $1,235 00

Total cost per ton 32

The New Western Mining and Reduction Company, owners.

T. C. Woodworth of Plymouth, superintendent.

Pocahontas Mine. — This property is 1^ miles east of Drytown, and
includes the Pocahontas, Edson, and California, the owners holding a
bond on the Maryland claim adjacent. A vertical shaft has been sunk
on the Pocahontas to the depth of 620 feet, with six levels. The forma-
tion is practically a black tufaceous, pitted slate, to the west of which
lie the Mariposa clay slates. Over 1000 feet of cross-cuts have been run,
extending from the Mariposa slates on the west to massive diabase on
the east. The property is provided with a good steam hoist, and a

10-stamp mill run by water power. There are 6 men employed. rThe

Pocahontas Improvement Company of Drytown, owners. Allen McWayne
of Drytown, superintendent.

Pioneer Mine. — It is 1 mile south of Plymouth, and comprises a mile
on the lode, which consists of two veins; the east or hanging-wall vein
of massive quartz, and the west vein banded structure. The latter is
usually the better vein. These veins occur in the black tufaceous slates
An inclined shaft has been sunk 500 feet on the foot-wall vein, and in
the several levels three shoots of ore have been developed. In some
respects these shoots of ore are similar to those of the Central Eureka at
Sutter Creek. The lower workings of the mine, however, are in low-
grade ore, and appear to have reached a zone of little or no pay rock

84 CALIFORNIA STATE MINING BUREAU.

which seems to be a peculiar characteristic of many of the most impor-
tant mines of Amador County. Geologically, the outlook for the future
of the Pioneer Mine may be considered as encouraging, as there is no
reason to anticipate that it may not at greater depth repeat the experi-
ence of the Kennedy and Argonaut, Central Eureka, and other mines in
this county. Dr. Thomas Boyson, owner.

Philadelphia Mine. — It is 4 miles north of Plymouth, near the Bay
State. Several years ago this mine was opened by means of a large cut
and drift, when operations were suspended, and the mine remained idle
until the spring of 1900, when a new double-compartment shaft was
started 1000 feet south of the old open cut. This shaft had reached a
depth of 80 feet early in June. Its hanging-wall is diabase; the foot-
wall is black slate. The vein formation is 20 feet in width. There are
kidneys of good rock on the foot-wall side. The shaft is equipped with

a water-power hoist, capable of going 1000 feet. J. J. Crawford, Claus

Spreckels Building, San Francisco, owner. Leased to J. R. Roaf et al.
of Toronto, Canada.

Ivanhoe Mine. — It is 1^ miles northeast of Plymouth. The mine
occurs in a zone of amphibolite schist, and is developed by a ver-
tical shaft 130 feet deep, and also by an inclined shaft 120 feet.
It has a 20-stamp mill and a steam hoist. It has been described in

former reports, and was closed down in the spring of 1900. Under

bond to the Ivanhoe Gold Mining Company of Salt Lake. E. Brent of
Sutter Creek, superintendent.

Shenandoah Mine. — It is 1^ miles northeasterly from Plymouth.
This interesting vein adjoins the Red Cloud, described in former reports,
on the south. The formation is diorite, which, near the vein, is altered
to amphibolite schist. The shaft, early in May, had reached a depth of
375 feet, partly on the vein, but the lower portion in the foot- wall.
Drifts were run at the 200 and 375 levels, the latter from a cross-
cut. There are two veins in this fissure, one a massive vein of quartz,
the other a banded or ribbon vein. On the south side of the shaft the
banded vein lies on the hanging-wall side of the fissure, but on the north
side it is found on the foot-wall side, being separated from the massive
vein by a small gouge. The massive vein appears to be the older, it
having been broken and crushed by the movement of the rocks. The
banded portion of the vein, however, is quite regular, and shows no
structural indication of disturbance. In addition to gold, there are
found iron, lead, and copper sulphides. The shaft has been sunk
between two shoots of ore, which have a southerly trend. The mine is
equipped with a steam hoist, but has no mill. There are 12 men

employed. Shenandoah Mining Company of Sacramento, owners.

S. K. Thornton of Plymouth, superintendent.

THE MOTHER LODE REGION — AMADOR COUNTY. 85

Red Cloud Mine. — It is H miles northeast of Plymouth, adjoining the
Shenandoah on the north. It has geological characteristics similar to
those of the Shenandoah. It is idle. The shaft has been sunk to a
depth of 365 feet, the upper portion of which was caved at the time of
my visit. The surface croppings are exposed in cuts, and show two
veins striking N. 13° W. and dipping 65 degrees to the east. The shaft
appears to have been sunk at a point where a fault has displaced the
vein, giving the appearance of two veins, whereas there is really but
one. The Red Cloud Mining Company of Stockton, owners.

(roivanus Mine. — It is 2 miles northeasterly from Plymouth. In this
])roperty there are several large lens-like masses of quartz striking
through a much foliated amphibolite schist. These lenses have a width
of from 1 to 8 feet, and occur across a zone of 150 feet or more in
width. They appear to converge northward. The ore is granular, and
of a dark blue color resembling some quartzite. It is said to mill $8
per ton. A three-compartment shaft (vertical) was being sunk during
the spring of 1900, which was calculated to reach the vein at a depth of
200 feet. At this mine was found an unusual arrangement of a hoist-
ing plant. The hoist, which is run by steam, is set opposite the
end of the shaft instead of at the side. This was done with a view, it
was explained, of leaving the ground for a permanent hoisting plant
unobstructed, and of permitting the temporary plant to be operated
until the new hoist could be placed in position. There are 8 men

employed. Gowanus Mining Company, owners. Mr. Rogers of

Plymouth, superintendent.

Bay State Mine. — It is 4 miles north of Plymouth. There are several
veins in this property. That known as the Bay State vein was formerly
worked by the Bay State Company to a depth of 830 feet; it was stoped
from the 400 to the 600 level. At the 750 level a cross-cut was run
east to the vein and two shoots of ore developed, one dipping north,
the other south. The north shoot is a banded vein, the south more
massive and mixed with slaty material. The sulphides found in the
south shoot were high-grade in gold. At 460 feet west, on the 750-foot
level, a west vein was discovered in the cross-cut, which is called the
Kretcher vein. This vein was observed at a point 346 feet west of the
shaft on the 300-foot level. The Kretcher vein has been developed for
a distance of about 300 feet, and consists of banded quartz of good
grade. At the time of my visit some improvements were being made
in the shaft, but the mine was not in full blast. The shaft will be sunk
an additional 300 feet. The mine is equipped with a good hoist, and
has a 10- stamp mill and an 8-drill air-compressor, all run by water.
The pumping is done by air. The mill has a capacity of 40 to 50 tons
daily. A 24-mesh punched tin screen is used. The pulp passes directly
from the battery to the vanners, of which there are four. The tailings

86 CALIFORNIA STATE MINING BUREAU.

are stated to contain but 21 cents per ton, chietiy in free gold. The
sulphides are shipped to the Drytown chlorination works. There are

12 men employed. The Globe Mining and Milling Company of

Stockton, owners. J. L. Bryson of Plymouth, superintendent.

Rhetta Mine. — This mine is about 4 miles north of Plymouth, adjoin-
ing the Bay State on the south. It is developed by means of a cross-cut
tunnel about 600 feet in length. There are two veins on the property.
One occurs at the contact of a diabase foot and a black slate hanging; the
other branches out from this contact vein, striking northward in the
hanging-wall slates. Both of these veins have been explored with
satisfactory results, the ore being hauled to the Bay State mill at a cost
of 30 cents per ten. A large amount of water is encountered, but this
causes little trouble, as it passes out through an adit tunnel. From the
Rhetta vein southward in the direction of Plymouth, a line of springs
marks the occurrence of fissures at or near the contact of the slates with
the greenstone, and although this section affords a good field for pros-
pecting, very, little has been done toward exploring. There are 8 men

employed. Rhetta Gold Mining Company of Stockton, owners.

J. L. Bryson of Plymouth, superintendent.

Talc Mines. — About 6 miles west of Sutter Creek is an interesting
occurrence of gold in foliated talc schist, which appears to be a structural
alteration of serpentine. On the Tonzi and Waechter ranches there are
several zones of this talcose rock, in which the gold occurs in extremely
thin plates in the foils of the rocks, much of which is thin as the finest
gold leaf; while presenting the appearance of richness, gold of this
character is very deceptive. On the Tonzi ranch, Mr. Tonzi has erected
an ingenious device for crushing this ore, and claims to have taken out
considerable gold at various times from the best selected gold-bearing
material found on his place. That this gold-bearing talc can be profit-
ably worked, is extremely doubtful; it is possible that if a zone of
sufiicient size, carrying $5 or more per ton in gold of the character
described, could be found, it might be profitably treated by some modi-
fications of the cyanide process.

Azula Mine. — This is 3^ miles northeast of lone. It is a pocket mine
in diabase, and has been worked with considerable success by its owners.
Mining here is carried on in rather primitive fashion, but evidently
with satisfactory results. The vein is from 16 to 18 inches in width,
the small stringers going into the main fissure from the hanging- wall.
Three men employed. Adams, Burris & Smith of lone, owners.

Nugget Mine. — This property is near the Azula, and is similar to it.
It has a small steam hoist, and a 5-stamp mill has been constructed

since my visit to the property; it was idle at that time. Dr. Adams

et al. of lone, owners.

THE MOTHER LODE REGION — AMADOR COUNTY, 87

Queen Mine. — This is in the same group with the Azula and Nugget,

and is geologically similar to the others. It has a small steam hoist.

Newman, Bagley & Frates of lone, owners.

Ranlett Copper Mine. — It is located 3 miles northeast of lone. The
ore-bodies occur in the greenstone schists in which are found many of
the copper mines in this State. The ore is that most common to copper
mines in the West, and is amenable to treatment by various smelting
methods. The development of the mine, while not extensive as com-
pared with the great gold mines of the State, is sufficiently so to show
that it is a mine of considerable possibilities. An examination of the
mine and maps, together with the statement made by Colonel Ranlett,
indicates about 30,000 tons of ore in sight, including that now on the
dumps. The ore may be divided into two classes: a vein of solid, mass-
ive, yellow sulphide copper ore, distinctly separated from the adjoining
rock, and in the foot-wall a zone of variable width, from 4 or 5 feet to
15 feet or more, in which occurs a large amount of iron sulphide, with
a small percentage of copper sulphide. In this zone there are segregated
bands of ore above the average of the zone in value, and which by
rough sorting may afford a valuable product, though, of course, not so
high a grade as that found in the massive vein. This ore contains
considerable silica, and may become valuable as a flux in treating the
more massive ore. The levels already opened are practically without
cross-cuts; at least, such as have been made are not in ore, and others
should be made in the foot-wall for the purpose of determining more
fully the extent and value of the low-grade zone. Manila ropes are in
use in this mine, steel ropes not having given satisfaction in former
years; but I believe that as so many years have elapsed since steel
ropes were employed here, it would be found that the modern steel rope
would prove superior to the large, cumbersome Manila ropes now in
use, even in the present old crooked shaft. I am positive that such
would be the case in the proposed new shaft, which would be sunk at a
uniform angle. A water-jacket smelter of 100 tons capacity daily was
built at this mine during May and June, 1900. Not yet blown in, June
10, 1900. H. G. Ranlett of Ranlett, superintendent.

CALIFORNIA STATE MINING BUREAU.

EL DORADO COUNTY.

This county, which in past years has produced a very large amount
of gold, is at present passing through a temporary period of inactivity,
due partly to scarcity of water and to other causes not wholly apparent.
There have been in the past in this county, and there are still, mines of
undoubted merit, a statement abundantly proven by its history, and
that the mines of El Dorado are exhausted cannot be entertained. Some
large and extensively equipped enterprises have come into prominence
and have been shut down since our last report, but the fact that there are
those who have been led into unprofitable investment by reason of the
exercise of too little caution should not, and probably will not, deter
others from engaging in the legitimate pursuit of mining enterprises in
this county on more conservative lines. No mining county in California,
and no mining region on earth, is wholly free from these monuments of
men's folly. It is a fact that in no county in California has mining
been carried on at less expense than in some of the mines of El Dorado,
and it still offers abundant legitimate and promising opportunities to
those with both the capital and experience to handle large low-grade
mines.

In passing northward from Amador County into El Dorado, the Cen-
tral Gold Belt, or so-called Mother Lode, appears to split up. The geo-
logical conditions for a distance of five miles in El Dorado County are
not wholly dissimilar from those of Amador, consisting essentially of
massive outcrops of white quartz at or near the contact of slaty rocks and
massive greenstones. These heavy outcrops of quartz are rarely gold-
bearing in amount sufficient to constitute payable rock, and they are
frequently accompanied, as elsewhere along the Gold Belt, by veins
having a slaty structure, in which the gold contents are sufficiently high,
in some cases at least, to afford profit.

When the neighborhood of the German Mine is reached, 5 miles north
of the Cosumnes River, we find a new and strange intrusive rock — one
with which we are not familiar in the region farther southward. A
study of this region shows that in proceeding northward some of these
rocks are of granitic type, ranging through grano-diorite and diorite to
quartz-porphyry, and other porphyritic rocks. As we go farther
northward, the rocks of this character increase in area, until in the
neighborhood of Placerville they largely dominate all other kinds,
although the rocks with which we are familiar farther southward (the
greenstones) may still be found. On a prominent hill just north of the

THE MOTHER I>ODK REGION — EL DORADO COUNTY. 89

Church Mine are large masses of rock of granitic type, of which a care-
ful investigation was made. The granitic outcrop was found to be half
a mile in width, striking with the general trend of the country in a
northeasterly direction. On the eastward, large ma.sses of diabase and
Huiphibolite schist are found. A number of rock specimens were
collected from various portions of this mass, and slides Avere i)repared
and studied by Mr. H. W. Fairbanks of Berkeley, whose report accom-
l^anies this bulletin. This investigation shows that specimens selected
at any particular portion of the mass, and assumed to represent the
entire intrusion, would be very misleading, for, in the several slides
made from specimens taken from different portions of the hill, we find
rocks of a decided acid character, and also those of basic kind, with
many intermediate phases. (Nos. 30, 31, 32, and 33.) The specimens
Nos. 26, 27, 28, and 29 are of similar rocks from Logtown and vicinity.
In some, hornblende is abundant, and in others augite is a prominent
constitutent; in still others, both of these bi-silicates appear. Some of
the rocks have abundant free quartz, in others none is visible to the
unaided eye. They also vary greatly in the kind and amount of feld-
spars they contain. Southward from this hill, in the direction of the
German, Pocahontas, and Starlight mines, and the country about Log-
town, are numerous intrusive dikes, large and small, of rocks of the
above described characteristics, and in some of the masses rich gold-
bearing deposits or veins have been discovered and worked, notably in
the Pocahontas at Logtown. In the neighborhood of Placerville is
found, near Diamond Springs, and extending northward beyond Placer-
ville, another section of the great dolomitic vein which is characteristic
of the Central Gold Belt in Calaveras, Tuolumne, and Mariposa Counties.
Here is seen the same broad zone of dolomite, or ankerite, in which
occurs an abundance of the beautiful, scaly, micaceous mineral, mari-
posite. Although the Pacific Mine in Placerville has been idle and
inaccessible for many years, the old dumps clearly show the character
of the geological formation. In this mine the ankerite has been com-
pressed, sheared, and deformed, the original material being altered into
a perfect talc schist. When this occurs, mariposite usually disappears,
or, if present, cannot longer be detected by its characteristic green color.
Serpentine also accompanies this belt, which is not an uncommon
accompaniment southward. In the Pacific Mine, the serpentine is
frequently found altered to a dark-green talc schist, which may be
readily distinguished from the white schist resulting from the altera-
tion of the dolomite.

The black slates found associated with the mineral veins between
the Cosumnes River and Placerville are chiefly the result of the altera-
tion of diabase tuffs, which has been described at length in the intro-
ductory paragraphs of this bulletin. Mariposa clay slates are also

90 CALIFORNIA STATE MINING BUREAU.

found. Owing to the very unsettled state of the weather and the diffi-
culties and delays attending transportation in March, the investigation
of this section was not carried north of Placerville until the summer
season.

German Mine. — It is 5 miles south of El Dorado. This was the first
accessible developed mine going northward last spring in El Dorado
County from Amador in which we find a material change in geological
conditions. The general formation of the country consists, as it does
farther southward, of massive diabase tuffs, amphibolite schists, and
the clay slates of the Mariposa beds. Here we also find the black slates
resulting from the alteration of the diabase tuffs which have been pre-
viously described as being intimately associated with the ore deposits
of the principal mines of Amador County. The gold-bearing veins of
the German Mine are found inclosed in these tufaceous slates, and the
vein structure does not differ materiall}'- from the veins of Amador.
The clay slates of the Mariposa beds lie both to the eastward and to the
westward of the main fissure, but not in contact Avith it. The most
striking geological feature of this mine is the intrusion of acidic dikes,
which present various phases ranging from quartz-porphyry to granite.
There were evidently several intrusions of different ages. These intruded
dikes have been sheared and have suffered deformation in a manner
similar to that characteristic of the altered diabase. These dikes in
width vary from a few feet to more than a hundred feet, and in more
than one place the larger dikes were found to contain zones of crushed
material into which free silica has infiltrated, together with iron sul-
phides and gold, but to what extent the zones are gold-bearing has not
as yet been determined. One intrusive mass which attracted my par-
ticular attention was found above the 100-foot level. It has been
intruded from the southward into the slates, and, as viewed in the mine
excavations, it looks like the stern of a great ship as it appears when
lying in drydock. A banded, slaty vein follows around this peculiarly
curved intrusion, having the granite on one wall and the slaty tuffs on
the other. The mine is equipped with a water-power hoist and a mill
of 10 stamps. The stamps weigh 950 pounds, and drop 6 inches, 100
times a minute. The discharge is 7 inches high, and a 30-mesh brass
wire screen is used. This mill has a capacity of 3:^ tons per stamp.
Below the battery plates, a shaking-riffle table has been introduced for
the purpose of saving any amalgam escaping the plates. It is said to
give satisfaction. A Wilfley concentrator is employed to concentrate
the sulphurets, which constitute about 1 i per cent of the ore. These

are shipped to Selby's reduction works. German Mining and Milling

Company of San Francisco, owners. C. 0. Richards of El Dorado,
superintendent.

THE MOTHER LODE REGION — EL DORADO COUNTY. 91

Buena Vista Mine. — It is 1 mile east of the German Mine, and 5
miles southerly from El Dorado. The veins are found in Calaveras for-
mation— mica schist at this place. A small vein running parallel with
the strike and dip of the schists has been followed for some distance in
search of pockets, with satisfactory results. A former operator who
prospected this mine, in some way was misled as to the value contained
in a schistose zone impregnated with iron sulphides, and expended
nearly $50,000 on the property, doing considerable development work,
erecting numerous buildings, and a mill. The rock proved almost
valueless, and the mine was closed. The present owners, however, are

doing well. C. 0. Richards of El Dorado, owner. Grant Hill of El

Dorado, lessee.

Last Chance Mine. — This vein is 1 mile east of Nashville, and is from
1 to 8 feet wide, occurring in the slates of the Calaveras formation. The
vein has a beautiful ribbon structure, and has been developed by a tun-
nel driven on the vein. A light-colored dike accompanies the vein. The
property is equipped with a 2-stamp mill run by gasoline engine. The

property is idle. A. C. Smith of Portland, Oregon, owner. H. E.

Smith, in charge.

The Center Mine. — Owned by a New York company, and is near the
Last Chance. Idle.

The Nashville Mine. — This mine is south of the Last Chance, and is

equipped with a steam hoist. Idle. E. J. Baldwin of San Francisco,

owner.

Madelina Mine. — It is 5 miles south of Diamond Springs. This vein
or zone is from 40 to 60 feet in width, in the Calaveras formation. There
is a gouge and dike rock on the foot-wall. The ore is pyrrhotite, chalco-
pyrite, and pyrite with gold. The ore is extremely hard, and a great
portion of it contains a very large percentage of the sulphides mentioned.
It offers a problem in economic metallurgy. The vein is developed by
means of a cross-cut tunnel 90 feet to the vein, and a drift along the
foot-wall 100 feet, connected by a raise 105 feet to the surface. Will-
iams & Bier of El Dorado, owners.

Noonday Mine (Copper). — This property, near the Madelina, when
visited, was simply a prospect having a 15-foot shaft and several open
cuts on a 7-foot vein consisting chiefly of iron and copper sulphides, the
latter ranging from a trace to 25 per cent. It may be considered a
promising prospect. Bonded to Dr. Procter of Placerville.

Montezuma Mine. — At Nashville. This property after an idleness
was about to start up in the spring of 1900. J. C. Heald of Nash-
ville, owner.

92 CALIFORNIA STATE MINING BUREAU.

Union Mine. — It is 3^ miles southeast of El Dorado. It was formerly
known as the Springfield, and was operated by Alvinza Hayward to a
depth of 1700 feet. Within the past two years the mine has been
operated by a company, and a 30-stamp mill built. On another group
of mines in the vicinity a new shaft was being sunk in March, 1900>
and though less than 100 feet in depth, a 20-stamp mill was being
erected. These properties are under the management of A. Harpending,
and were the only ones visited during the season where inspection was
denied and information refused. It was currently reported that a large
amount of gold was being taken out, but I was unable to confirm this
report. There are 45 men employed at these two mines.- — -A. Har-
pending of El Dorado, superintendent.

Church Mine. — It is located 8 miles south of Placerville, and 2^ miles
from El Dorado. Three veins occur in the slates; they are well defined,
and have hard walls and a gouge on both foot and hanging walls. The
two veins mostly developed are of variable thickness, laminated, and
carrying considerable sulphurets. There is also an east vein, known as
the Union, which is being worked near the south end of the property on
the adjoining Union Mine. Surface prospects on this lead in various
places give a result of from $2.35 to $26 per ton. The vein worked by
the former company was termed the Kidney vein, and has been worked
to a depth of 1350 feet, taking out the best of the ore and leaving the
low-grade ores. This vein averages 5^ feet in width, and the rock taken
from it milled from $28 to $30 per ton. The prospective value of the
mine is based on the value of the west vein, first discovered on the 350-
foot level while sinking the shaft on the Kidney vein. There were
milled from this ledge 3000 tons of ore taken from the various levels
from the 350-foot to the 1200-foot level, which returned $2.50 per ton
free gold and about 2 per cent sulphurets, worth $67 per ton; the tail-
ings, owing to a lack of facilities in the mill, averaged $1.27. This vein
in many places is from 14 to 20 feet wide, averaging 8 to 10 feet. The
main shaft is 1200 feet deep vertically, with a 40-foot sump, and has
three compartments. Stations are cut at each level. The mine is
equipped with a water-power hoist, and is provided with 3000 feet of
steel cable. The compressor has a capacity of five 3-inch drills. The
pumping plant, consisting of plunger and jack-head pumps, has a
capacity of 150,000 gallons per day, which is about double the amount
of water the mine makes. The mill has ten 950-pound stamps, four Frue
concentrators, clean-up barrel, pans, etc. The machinery is run by
water power taken from a reservoir owned by the company; at the mill

there is a head of 485 feet. Church Mine Development Company of

San Francisco, owners. John Ross, Jr., of Sutter Creek, superintendent.

Griffith Mine. — It is half a mile southeast of Diamond Springs and
half a mile from the Larkin Mine. Since the last report, this mine, at

THE MOTHER LODE REGION — EL DORADO COUNTY. 93

that time a mere prospect, has been elaborately equipped with hoist,
mill, etc., and an expensive electric power plant, by a Scotch syndicate.
After a few months of active operation, the mine was closed down and
nothing has since been done there. It is locally reported that it did not

pay. Griffith Mining Company of Glasgow, Scotland, owners. G. P.

Gow of Stent, agent.

Larkin Mine. — One-half mile east of Diamond Springs. The great
dolomitic vein passes through this property, in addition to which there
are several other, though less prominent, veins. It is upon one of the
latter, which occurs in the hanging-wall slates of the dolomitic vein,
that operations are at present being conducted. This vein is accom-
panied by a small dike of diabase, and possesses the usual character-
istics of veins in slate. The dolomitic vein is 80 feet in width, and is
altered more or less to talc schist. The dolomite here appears to contain
iron carbonate, and is properly ankerite rather than dolomite. The
ankerite vein is also cut by dikes, a feature not observed elsewhere, and
the foot-wall portion, for a width of several feet, is impregnated with
quartz and pyrite, but no exploration had at the time of my visit been
conducted on this mineral zone. There are several small veins in the
amphibolite schist of the foot-wall, but these, too, remain unexplored.
This mine has a 10-stamp mill, the stamps weighing 1000 pounds, drop-
ping 110 times a minute. A No. 1 punched tin screen is employed.
The discharge is 9 inches high, and the capacity of the mill under these
conditions is said to be a little in excess of 3 tons per stamp per day of
twenty-four hours. The ore contains H per cent of pyrites. These have
been shipped to Selby's, but experiments with the cyanide process have
demonstrated that the gold can be extracted from the sulphides by this
means without preliminary roasting or other treatment. Of the gold
obtained by amalgamation, about 55 per cent is recovered in the battery.

An ingenious experiment has been tried by the superintendent with a
view to prevent scouring of the inside copper plates. This consists of a
cast-iron plate having the shape of a segment of a cylinder to fit the
copper plate. It is ^ inch in thickness, with slots ^ inch in width and
20 inches in length. Within these slots the amalgam accumulates and
remains. Concentration is accomplished on a single Wilfley table. A
vertical shaft has been sunk 600 feet, and a cage is in use. There are

35 men employed. Larkin Mining Company of San Francisco,

owners. G. B. Jacobs of Diamond Springs, superintendent.

Selby Mine, — It is 1 mile east of Diamond Springs, near the Larkin
Mine. Idle.

Marguerite Mine. — It is 1 mile east of Diamond Springs, near the
Larkin Mine. Idle.

94 CALIFORNIA STATE MINING BUREAU.

Tin Cup and Ribbon Rock Mines. — These mines are 2 miles south of
Placerville, and are being operated under bond by A. Hayward of San
Francisco. When visited, the main shaft was down 100 feet in "ribbon
quartz " 5 feet wide showing gold, and for amount of work done it was
considered the best prospect in that section of the country. There are 10
men employed. Since writing the above the shaft has been sunk to 200
feet and a heavier hoist installed. E. A. Davis of Placerville, super-
intendent.

Gentle Annie Mine. — It is 1 mile north of Placerville. This comprises
a property 1000 feet by 1700 feet, covering five parallel veins, of which
the principal one appears to be the dolomitic vein, which has been pre-
viously described as characteristic of some portions of the Gold Belt,
The mine, while extensively developed and equipped with a lO-stamp
mill, has been idle since October, 1899, awaiting adjustment of the affairs
of the Melton estate. There are two large air-compressors and a hoist,

which may be operated by either water, air, or steam. B. G. Parlow

of Placerville, superintendent.

Revera Mine. — On Texas Hill, 3 miles east of Placerville. This is a
drift mine, to which a bedrock tunnel was being driven 900 feet to the
channel, which, on March 15th, had penetrated a distance of 600 feet-
The property is equipped with a mill having a Dodge pulverizer with a
capacity of 125 tons daily, running 15 revolutions a minute; there is
also in the mill a Krough shaking-riffle. The mill is run by water power
under 169 feet head. A self-discharging tank was a feature of the
works, so arranged as to sluice out accumulated tailings. Since
writing the above the tunnel has reached the channel, and is reported
to be in pay gravel. Parker Bros, of Placerville, owners. C. L. Parker,
superintendent. *

Ellen Taylor Drift Mine. — It is 4 miles west of Indian Diggings.
Sluicing and piping were in progress in the spring of 1900. There were

11 men employed. A. B. Spreckels et al. of San Francisco, owners.

F. J. R. Dawson, superintendent.

Umatilla Drift Mine. — This is in El Dorado Count}'-, 12 miles north-
east of Plymouth, Amador County. The mine has been worked steadily
for the past two years. The gravel channel varies greatly in width, and
ranges from a few inches to 4 feet in thickness. The gravel is crushed
in a Krough hexagonal mill, similar to the Dodge pulverizer, and has a
capacity of 250 tons per day. Below this machine is a shaking-riffle,
in which the gold is caught. The machinery is operated by water

power. Umatilla Mining Company of San Francisco, owners. C. O.

Richards of Ono, superintendent.

Placerville Slate Quarry. — It is \\ miles north of Placerville. Here a
quarry has been opened upon a reef of slate 150 feet or more in width,

THE MOTHER LODE REGION — EL DORADO COUNTY. 95

standing nearly vertical. A large portion of this slate appears to be of
merchantable quality. The slate, after having been prepared for mar-
ket, is hoisted to the top of the hill on an inclined tramway, the car
})eing run from the quarry track directly upon the car or giraffe. The
tramway is double. On the opposite track from the giraffe is a car
carrying a steel cylinder with a capacity of several hundred gallons.
This is filled with water at the top of the incline, and when its weight
overbalances the weight of the giraffe, carload of slate, and cable, it
moves downward, hauling the car up the incline, its speed being con-
trolled by a brake at the head of the tramway. The water cylinder
discharges automatically at the foot of the incline, when the giraffe and
car return to their places at the loading station. This company has
taken contracts to furnish slate for the buildings of the Mountain Cop-
per Company at Keswick, Cal.; for the Government, and elsewhere.

There are 10 men employed. Placerville Slate Company, owners.

G. W. Cummings of Placerville, manager.

Pocahontas Mine. — It is 3 miles south of El Dorado. The vein,
which lies at a low angle with a curving strike, occurs in a feldspathic
porphyry (No. 26), through which is scattered many crystals of bronze-
colored mica. This peculiar rock when examined in sections under the
microscope is seen to be a diorite-porphyrite. The property was at one
time well equipped with machinery, having hoisting works and a 10-
stamp mill, but these have been removed and the mine has been idle

for some time, although at one time producing handsomely. Q. A.

Chase of San Francisco, owner.

Minnehaha Mine. — This is 3 miles south of El Dorado P. 0., near
Logtown. The vein occurs in quartz-porphyry much silicified, and
containing a small amount of iron sulphide with coarse free gold. The
vein strikes N. W. and dips N, E. about 10 degrees below the horizon.
There is no parting between the vein and the country rock, the ore
passing over gradually to the country rock. In one place along the
surface in the hanging-wall was found a zone of porphyry with many
quartz seams carrying gold. These were dipping toward the flat vein,
but had not been reached in the mine workings. The rock is crushed in

a 4-stamp mill. No concentrators were in use; 8 men employed.

Minnehaha Gold Mining Company of San Francisco, owner. Froehlich
& Perham of El Dorado, lessees.

Starlight Mine. — Three miles south of El Dorado. The ore in this
mine occurs in large lenses in a much altered, silicified diabase. There
are several shafts on the mine provided with steam hoists, and there is
a 10-stamp steam mill, which is supplied with ore from the several
shafts by means of a rope tramway, having a capacity of 35 tons a day.
The ten stamps weigh 1000 pounds each, and drop 6 inches 100 times a

96 CALIFORNIA STATE MINING BUREAU.

minute. The discharge is 7^ inches high. A No. 8 vertical-slot screen
is employed. Concentration is eftected by the use of two Union
machines and a canvas plant. The ore contains 2 per cent of sul-
phurets — pyrite, galena, and arsenical sulphide. The value, how-
ever, is chietly in free gold. Starlight Gold Mining Company of San

Francisco, owners. J. A. Vance of El Dorado, superintendent.

Oro Fino Mine. — This property, which has been repeatedly described
in former reports, was found working as usual. It is situated 5 miles
south of Diamond Springs. The vein, which is 40 feet wide, consists of
a dike-like mass of diabase breccia which has become silicified and
impregnated with finely disseminated auriferous pyrite. Many small
seams of calcite traverse the rock in every direction. • Both hanging
and foot-wall country are diabase, but little altered even in close prox-
imity to the vein. The vein material is extremely hard, and all ground
is broken by machine drills, No. 1 Judson powder being used. A
vertical shaft has been sunk to a depth of 200 feet, where it turns at an
angle of 40 degrees and continues to a depth 'of 540 feet on the vein.
The hoist is operated by compressed air. The mine has a mill of 30
stamps, which weigh, when newly shod, 1250 pounds. These drop 7
inches 105 times a minute. A 40-mesh punched tin screen is used, the
capacity of the mill being 85 tons daily. No amalgamation is attempted
inside the batteries. About one third of the values are in free gold,
which is collected on the outside plates. The sulphides are concen-
trated on belt machines, and are treated in a chlorination plant owned
by the company. Its daily capacity is 4 tons. A rotary conical
breaker of the Gates type, being cast extremely heavy, has been found
satisfactory in crushing this unusually hard rock. This mine has

recently been shut down. Hayward & Lane of San Francisco,

owners. E. T. Kane of Canyon P. O., superintendent.

Vandalia Mine. — This interesting mine is situated about half a mile
northerly from the Oro Fino. It has come into renewed prominence
since the publication of the last report. In many respects it is entirely
unlike others of the Gold Belt, though mines of somewhat similar
character are known in Arizona, Nevada, and other portions of the
Great Basin country. A description of the old Vandalia Mine will be
found in the Vlllth report of the State Mineralogist. When being
worked at that time, the ore was considered free milling, but still so large
a percentage of the values was lost in tailings that the character of the
mine was essentially the same then as now, though richer. The large
ore-shoots developed by the present owners are not amenable to amal-
gamation, but the cyanide process, which has been applied in a rather
rudimentary manner, has been found to operate satisfactorily.

When the present owners first visited the property, they tested the
old tailings dumps which resulted from the operations of former owners,

THE MOTHER LODE REGION — EL DORADO COUNTY. 97

and these were found to contain upward of $15 per ton in gold. A
series of cyanide experiments soon demonstrated the adaptability of this
ore to that process. The tailings dumps were first worked, and paid
handsomely. Then the ore-bodies were attacked, and work has con-
tinued uninterruptedly since.

The ore deposits are found in a highly silicious felsite, having a
semi-schistose structure, and in many respects are not unlike the quartz
schists found in the Calaveras formation, though these latter are gen-
erally metamorphosed sandstones, and not of intrusive origin. The
ore-shoots average over 80 feet in width and 300 feet in length, and cut
both the strike and dip of the inclosing formation. The normal ore is
essentially the quartz schist above described, heavily impregnated with
iron sulphide, the oxidation of which has produced a mineralized zone
extending from the surface to a depth of 100 feet or more, forming a
reddish-brown iron cap or gossan. These ore-shoots are reached through
adit tunnels, the lowest of which will, when extended, cut the ore-bodies
300 feet below their apex, and tunnels may be run at still lower points.
The ore for most part, though heavily mineralized and oxidized near
the surface, does not prospect at all in free gold, but always assays.

The mill found in operation at this mine was of home construction,
made by the owners themselves, and is a rude, though ingenious affair, but
not well suited to the class of work it is required to perform. It consists
essentially of a revolving hollow cylinder resting upon four wheels or
carriers, and provided with iron bars arranged transversely to its length,
having about ^ inch space between them, similar to the Dodge
pulverizer. In the interior of this cylinder are three so-called cams,
which are really elevated ribs extending lengthwise of the cylinder and
distributed at equal distances. The crushing device consists of three
cylinders of iron, each 10 inches in length and 8 inches in diameter.
These are connected at their ends by links, iron rods extending'
outwardly from each end of the connected cylinders to posts situated
outside the machine. As the cylinder revolves, the cams, each in turn,
lift the linked crushers until, clearing themselves, they fall backward a
few inches, crushing the soft ore; this being repeated as long as the
machine is in operation. The rock is fed through the open end of
the cylinder, passing out between the bars, when crushed fine enough to
pass the half-inch space between them. The machine is driven by a
belt, power being furnished by a gasoline engine. As a result of this
very coarse crushing, extraction of gold rarely exceeds 60 per cent.

The cyanide plant is situated about 200 feet from the mill, at the foot
of an inclined tramway. The plant consists of two clear- water tanks,
two stock-solution tanks, six percolation vats of 10 tons capacity each,
two gold-solution tanks, and two sump tanks, together with the neces-
sary precipitation boxes. The ore from the mill is delivered to the
7 — MB

98 CALIFORNIA STATE MINING BUREAU.

cyanide plant by cars running on a double tram, the cars working in
balance. Between the line of percolation tanks is a track running the
full length of the plant, with a turntable at the center. The ore is
dumped directly into the tanks, and distributed by shoveling at a cost
of 25 cents per ton, including the cost of tramming. The cyanide solu-
tion is worked at about 0.25 per cent, with a consumption of 15 per
cent cyanide. The ore is charged as described, and the solution turned
in on top of the charge upon burlaps. It is allowed to stand three
hours, when a valve is opened, and a pump connected with the weak
solution in the sump tanks is started. This solution is pumped on at
a rate equaling the progress of leaching, until the amount of solution
charged is equal to the weight of the ore. The percolation process is
usually completed in forty-eight hours. In the bottom of the precipi-
tating-box an ordinary punched tin mill screen is placed, which keeps
perfectly clean and shows no sign of corrosion. The cost of treatment

is stated by the owners to be 50 cents per ton. Seymour & Staver,

owners and managers. Shingle Springs P. 0. It is stated that this mine
has recently passed into other hands, and is to be extensively equipped
and operated.

Fortuna Mine. — It is 5^ miles south of Shingle Springs, near the Oro
Fino Mine. At the time of my visit last spring, the mine and 5-stamp
mill were idle, but the owners were building a ditch in anticipation of
resuming operations. Hale & Boughman of Canyon P. 0., owners.

Monitor Mine. — It is 3 miles south of Canyon P. O. The vein occurs
at contact of slate and greenstone. It has a shaft 60 feet deep, with a
50-foot drift at the bottom. The vein is 7 feet wide, and the rock is said

to mill $6 per ton. The mine is provided with a steam hoist. C. E.

Schenks of Canyon P. 0., owner.

Spanish Dry Diggings. — At this place, ^ mile northwest of Greenwood,
a few men are making a living working the rich seams. No organized
operations are in progress.

Altman Mine. —Near Greenwood. The property comprises 3000 feet
on the lode. The principal development consists of a tunnel 500 feet
long, which gives 250 feet backs. The mineralized zone is about 100
feet wide, and is stated to mill $3 per ton. A strip along the foot-wall,
however, runs much higher. A 10-stamp mill formerly on the property
burned. Two men are at work John Smith of Greenwood, owner.

Gopher-Boulder Mine. — It is 1 mile north of Kelsey. The property
was well equipped with electric power, but the generator house on Rock
Creek burned. This is to be replaced. The mill contains 20 stamps and
two 5-foot Huntington mills; these latter are stated to be equal to the
20 stamps in capacity. The vein is from' 30 to 100 feet wide, but low-
grade. A shaft has been sunk on the vein 250 feet, and a large open cut
has been made in a zone of quartz and greenstone schist. Mining can

THE MOTHER LODE REGION — EL DORADO COUNTY. 99

be carried on here very cheaply, as the company owns its power. At
tlio Dalmatia, a mile distant, mining and milling were formerly carried
on at a cost below 50 cents per ton. The Gopher-Boulder is idle, but it

was stated that work would, in all probability, soon be resumed. W.

A. Bell of San Francisco, owner. W. H. Husband of Kelsey, manager.

Hayward Hydraulic Mine. — At Indian Diggings, on an ancient channel.
There is ahout 150 feet of gravel, overlaid by over 100 feet of volcanic ash.
The mine was extensively worked during the spring and summer seasons
by hydraulic methods. About 1000 inches of water is employed in
washing. Plymouth Consolidated Mining Company, owners.

Eureka {Strale) Slate Quarry. — This property, situated near the vil-
lage of Kelsey, was in operation during the summer, employing 20 men.
Steam-operated power drills are in use. A superior quality of slate is

produced at this quarry. Eureka Slate Company, owner. W. A.

Winsboro of Kelsey, superintendent.

Zantgraf Mine. — It is 7^ miles east of Newcastle, Placer County, and
has been in operation for fifteen years. The principal shaft is sunk at
an angle of 45 degrees in grano-diorite. It is 1125 feet deep. There are
10 levels open in the mine. Power drills are employed. Two shoots of
good ore are on the main fissure, with 300 feet of low-grade rock inter-
vening. On the 300-foot level a cross-cut, run 150 feet west, encountered
a parallel vein, in which a shoot of pay rock has been developed. The
sulphides, constituting -I of 1 per cent, are high-grade, and with increas-
ing depth it is stated that the percentage of sulphurets increases with-
out any noticeable decrease in free gold. The north shoot on the main
vein has been explored for a distance of 300 feet, and the face is still in
good ore. The same shoot is being opened on the 300-foot level, where
it is 600 feet long, and is also being developed on the 700 and 800 levels.
On the 1100-foot level the shaft is in low-grade rock, but the north shoot
is expected at the 1200, as it is pitching south. It is 150 feet from the
shaft to the south shoot. The property is equipped with 25-stamp millj
and has a duplicate steam plant for both hoist and mill, though depend-
ing, under ordinary condition^, upon electric power. The company owns
its power plant, which is located on the American River half a mile
distant from the mine. The machinery was being renewed the past
summer at the time of my visit. The stamps in the mill weigh 1035
pounds, when new. A punched tin screen is in use; the capacity is
about 5 tons per stamp, with a discharge 5 to 6 inches high. This large

capacity is due, of course, to the unusually coarse screen. Montauk

Gold Mining Company of New York, owners. Edward Goodwin of
Newcastle, superintendent.

Jach Hanley Mine. — It is 2^ miles south of Greenwood. Prospecting

is in progress. A rocking mill is in use. Four men are employed.

C. A. La Graves of Greenwood, superintendent.

100 CALIFORNIA STATE MINING BUREAU.

CALAVERAS COUNTY.

In this county the mining industry is unusually prosperous, more so
than in many years past. There are at work, and paying, no less than
a dozen large mines, including v three hydraulic mines, besides a great
many small concerns, and a good deal of active prospecting is now
in progress. Since the last report, a number of new enterprises
have started up which are now idle, having proven unsatisfactory to
the investors, but there are others which have, in a great measure,
redeemed these more unfortunate ventures. Notable among the
latter class is the Sheep Ranch Mine, which, after an idleness of
nearly six years, has been reopened, and is again an active and, it is
said, a profitable producer. The copper mines at Campo Seco are also
being operated successfully, and in the Salt Spring Valley at Hodson
the Royal Consolidated Mines are being worked on a much larger scale
than heretofore. On the whole, Calaveras County may be said to be in
a very prosperous condition. The development and exploitation of the
new ore-bodies found in the Utica-Stickle and Gold Cliff properties at
Angels will give a new lease of life to these important producers, and
the operations of the Melones Consolidated Mining Company at Carson
Hill will be among the most extensive in the State when carried to
completion.

Gwin Mine. — It is 6 miles south of Jackson, Amador County. In
its earlier history this mine was worked to a depth of 1540 feet through
inclined shafts. Operations were suspended in the fall of 1882, and the
property remained idle until 1894, when the present operators reopened
the mine. A vertical shaft was started in the hanging-wall slates 485
feet from the vein. Work was commenced on May 1, 1894, and has
progressed continuously since, with the exception of a period of about
four months, when an attempt was made to unwater the old workings
by means of a bore-hole to avoid flooding of the new workings from
the old. It eventually became necessary to remove the water through
the shaft of the old workings. This new shaft has continued to a depth
of 1660 feet, having passed through the vein at about the 1200-foot level.
There are tanks at the 300-foot level and at the 700-foot level. At the
latter a cross-cut was run west from the station 374 feet, through slate
to and beyond the vein, the foot-wall of which was reached 124 feet
west of the shaft. At the 1000-foot level a cross-cut was run 69 feet
west through the vein, which was here 15 feet 6 inches wide, the foot-
wall being 58 feet west of the shaft. The foot-wall of the vein was

THE MOTHER tODE REGION — CALAVERAS COUNTY.

101

encountered in the shaft 1245 feet from the surface. Cross-cuts in the
lower levels run to the westward have encountered two small veins
and two dikes of light-gray intrusive rock. The first vein encountered
is very persistent in strike and dip, though usually small. It has pro-

Me-TWOD of- Tin^^ERINC^ in Q>\N\N A^lNErr

Fig. 28.

duced some rich ore. The ore-shoots of the main vein are of great
length, varying in width from a few inches to 20 feet. Gouge is always
present on the foot, and sometimes on the hanging-wall. The slates
have a tendency to swell, and are the cause of considerable expense,

102 CALIFORNIA STATE MINING BUREAU.

but cannot be compared in this respect to some of the Amador County
mines. The vein is usually banded, and exhibits a branching tendency,
there being many spurs running into the hanging-wall, but few into the
foot. The lenses of quartz which are characteristic of this vein fre-
quently build up a narrow into a large vein by splicing, and sometimes
by overlapping. There is some black slaty material in the vein, but
less than is found in many similar mines elsewhere. Large masses of
the vein quartz are found crushed by pressure and movement, and in
some places the quartz disintegrates rapidly from exposure by reason of
the slaking of the carbonate of lime, which occurs in considerable
quantities.

The mine is systematically opened, and substantially timbered with
Oregon pine. The framing of timber is mostly done by machinery.
Filling for the stopes is usually obtained from the hanging-wall, and
broken by machines in chambers excavated for the purpose. Where
feasible, inclined raises are put into the hanging-wall, and the chambers
opened out from the raise, the rock broken passing by gravity down the
incline into the stopes beneath. Where the character of the hanging-
wall adjacent to the vein is such as to cause the ground to cave readily,
level cross-cuts are run from the stopes into the hanging-wall, and
chambers opened out at a safe distance from the vein, the filling being
carried to the stopes in wheelbarrows. The Gwin Mine is one of the
best managed properties it was my pleasure to visit, everything being
done systematically with a view to producing the best economic results.
The sketch (Fig. 28) represents the method of timbering stopes in the
Gwin Mine. I was told, when at the mine, that the management had
under consideration the advisability of running a lateral drift in the
foot-wall, and opening the naine something on the lines suggested in the
first part of this bulletin, under the head of " Methods of Mining."

Geologically, the Gwin Mine presents a striking contrast, when com-
pared with the more important mines of Amador County. Here the
vein occurs in the smooth, satin-like clay slates of the Mariposa beds,
which are absolutely free from the pitted appearance so characteristic
of the slates accompanying the ore-shoots of Amador County, which have
been fully described under the head of Amador County, and also under
the head of "General Geology of the Gold Belt." The formations
encountered in sinking the Gwin shaft are diabase-tuff, clay slates, and
small acid dike rocks. In the lower portion of the mine, a coarse,
tufaceous rock, locally but erroneously called pudding-stone, has been
encountered, which has been the cause of considerable difficulty in
timbering, in carrying on mining operations. It is the intention of the
company to make some changes in their shaft, and to sink to greater
depth. What may be developed in this property at great depth is a
matter of more than ordinary interest. Its present lowest level still
lacks about 1000 feet of being as deep as the Kennedy, and it is a well-

THE MOTHER LODE REGION — CALAVERAS COUNTY.

103

6c?£tN Fl^AT'^l

/\H0

vJzdke.

Chuck ?)i^ocK

known fact that the ore-bodies in the lowest workings of the latter show

no deterioration in value. Gwin Mine Development Company of Han

Francisco, owners. J. J. Crawford, secretary, Spreckels Building, San
Francisco; F. F. Thomas, Gwin Mine, Calaveras
County, superintendent.

Gwin Mill. — The mill at the Gwin Mine now
comprises 80 stamps, and is operated under the
direction of Mr. J. E. Taylor. The stamps when
new weighed 850 pounds, and drop 6^ inches 92
times per minute. The height of discharge is from
7 to 9 inches, and is regulated by three chuck-
blocks. No. 16 brass wire screens are in use, and
last one month. The screens
are changed daily, scrubbed
and dried, so that practically
the screens are daily as good as
new, until worn out. The size
of the screen opening is 5 inches
by 48 inches (discharge area).
All screens are secured to small frames, which are
inserted above the chuck-block and beneath the
front board of the main screen frame, being secured
by a wedge. (See sketch, Fig. 29.) The capacity
of the mill, under the above conditions, is 4^ tons
per stamp daily. To prevent scouring of the inside
plate an iron rod is bolted to the plate. Its posi-
tion is shown in the figure. The
pulp from the battery falls onto the
iron lip of the mortar, thence by a
3-inch fall onto a narrow board, and
thence onto the apron plates, which
are 48x60 inches, set at the grade
of 2 inches to the foot. Thence it
passes to the sluice plates, which are
24x120 inches, having at the end
a trap for the purpose of catching
mercury and amalgam. From the
plates, the pulp passes to the van-
ner distributers, and from the van-
ners the tailings go to waste. In
the canon some distance from the
mill a canvas plant was constructed
by experimenters, some time since, but its use was discontinued. The
sulphides, collected on the vanners, are heavy, probably coming from
the quartz, and the values from the sulphides are largely confined to

ronga

Fig. 29.

104 CALIFORNIA STATE MINING BUREAU.

this class of material. A quantity of fine sulphides escapes with the
tailings, which probably come from the slaty material. They are low-
grade, and do not even justify the inexpensive further concentration on
canvas tables.

The concentration plant consists, in the original mill, of sixteen
4-foot Frue vanners, one of which is of special design called the " Gwin."
In the 40-stamp addition recently made to the mill there are sixteen
6-foot machines, all of this special design. These machines have an
iron frame with cross-rods both longitudinally and transversely of the
machine, which gives it great rigidity, and demands little attention
when having been properly adjusted. The sulphides contained in the
ore range from 1^ to 2 per cent. These are shipped to Selby's reduction
works. Mr. Taylor states that the tailings escaping from this mill
average about 25 cents per ton. The entire plant is run by water
power, under a 400-foot head. A 6-foot Pelton wheel runs the 80
stamps, and a 24-inch wheel the concentrating machines. Power is dis-
tributed from the line shaft, which is beneath the feeder floor, by vertical
belts to the cam-shaft pulley. The power is transmitted from the main
wheel to the line shaft by a hemp rope 5 inches in circumference.
Space has been provided in the building for an additional 20 stamps, for
which there is abundant power. An electric plant has been installed
for lighting the property. The mortars in the old mill differ somewhat
from those in the new mill, those in the new mill being narrower. The
mortars are lined throughout with deep plates and are thoroughly
modern.

Sheep Ranch Mine. — This is at Sheep Ranch and on the east belt, 17
miles northeast of San Andreas. The mine was operated in former days
by Haggin, Tevis, and Hearst, but was closed down in 1893, when a
depth of 1200 feet had been reached, after producing about $3,000,000.
It remained idle until 1898, when it was reopened by the present owners,
who cleaned out the old shaft, retimbered it, installed a new and heavy
plant of machinery, and thoroughly equipped the mine, in the belief
that it was not exhausted. They went into the old workings on the 1200-
foot level; extended them; drove the Pioche tunnel to a connection with
the shaft at the 300-foot level, and started upraises at various points on
the 1200-foot level, and began at once taking out rich ore. A new 20-
stamp mill lias been built; two air-compressors, and an electric plant
and machine shop have been provided. The property comprises twenty-
one claims, which include five known veins. The formation is a rather
coarse mica schist, cut by dikes of diorite and coarse-grained granite.
The Sheep Ranch vein, which is, so far as known, the hanging-wall vein
of the series, is from a few inches to 3 feet in width, averaging about 18
inches. The ore is generally high-grade, often showing free gold, one
shoot in particular now being operated south of the shaft above the 1200-

THE MOTHER LODE REGION — CALAVERAS COUNTY.

105

foot level, producing a dark blue, almost black, quartz, rich in free gold.
The most of this rock is in demand by the manufacturers of jewelry, it
thus paying far better than to crush it in the mill. The quartz usually
occurs as a continuous waving vein, or as a succession of disconnected
lenses, often contorted and twisted suddenly from its course, and when
this occurs visible gold is usually abundant.

The accompanying sketch (Fig. 30) represents a characteristic sec-

m\s

Vertical Cross a)&crioN q^ i2oofLj.\/Eu

OF- ^HEErP f^ANdN /^ I N Er sl-joWir^o charac^eris-ri c_
Vcir\ Porn9a+ior\.

Fig. 30.

tion of the Sheep Ranch vein. Each of the several veins in this prop-
erty has considerable superficial development,

A shaft is being sunk on the Lodi claim, one of the Sheep Ranch
group, about 700 feet southwest of the main shaft. It is said that in
former years very rich ore was taken from the Lodi vein. All machinery

at the Sheep Ranch is operated by steam. Sheep Ranch Mining

Company, owners, 320 Sansome Street, San Francisco. D. Gutmann,
manager.

Veritas {Bode or Fellowcraft) Mine. — At San Andreas. Since the last
report, an inclined shaft (at an angle of about 55 degrees) has been

106

CALIFORNIA STATE MINING BUREAU.

sunk 200 feet on a vein cutting through mica schist. At the 100-foot
level a cross-cut has been run east to a zone of amphibolite schist and
quartz, 4 to 8 feet wide. On the 200-foot level a cross-cut has been
extended 135 feet east of the shaft to this vein, which is there 8 feet
wide. The mine is equipped with a lO-stamp steam mill and water hoist,
but is idle. On the hill, back of the shaft, is a zone of mineralized quartz
schists, which prospects in gold, and is apparently the most promising
part of the property, but nothing has been done with it in the way of

development. Veritas Gold Mining Company, owners. F. J. Solinsky

of San Andreas, agent.

Commodore Mine. — One mile north of San Andreas, on the Mother
Lode. A vertical shaft has been sunk 80 feet, thence continuing at an

Cross OECTIOH ^ihowin* succcss'ioo of formations a"!""
(oMMooof^s: /^iNt, 1 mile H. of SANT^NOf^eAa . CalaVeras Co. C-ai_.

Fig. 31.

angle of 75 degrees to the eastward to a depth of 300 feet. A level had
been run north 250 feet April 1st, developing a wide zone of mineralized
rock, which in its normal condition is quartz diorite (No. 21). This
occurs as a wedge-shaped intrusion, coming from the north. Serpentine
forms both the foot and hanging walls of this lode. To the westward,
on the Masterson claim, is a broad zone of ankerite, so frequently men-
tioned as occurring elsewhere,- with its massive quartz outcrop and
characteristic mariposite, and to the eastward of the serpentine the
formation is a normal diabase. A cross-section is illustrated in the
sketch (Fig. 31).

The Commodore vein is somewhat of an anomaly in this region. It is
a matter of interest to know that the quartz diorite, the alteration and
mineralization of which form this ore-body, is almost identical, both
mineralogically and in physical appearance, with a dike of quartz-

THE MOTHER LODE REGION — CALAVERAS COUNTY. 107

diorite (No. 20) intruding the amphibolite schist in the Union Copper
Mine at Copperopolis, in this county. On the hanging-wall side of the
Commodore vein is a zone of crushed material, 4 feet in width, in which
occur rhombic crystals of dolomite. These, upon being fractured, may
be observed to contain visible particles of gold. The mine is equipped

with a steam hoist. There are 10 men employed. Commodore Gold

Mining Company of Stockton, owners. W. H. Glarey of San Andreas,
superintendent.

niinois Mine. — It is 6 miles south of San Andreas, on the Copper-
opolis road, near the Demarest Mine. Since the last report it has been
equipped with a steam hoist and a 10-stamp mill. An inclined shaft
has been sunk to a depth of 200 feet, and two levels opened. There are
two veins, one running N. 5° E., and the other N. 30° W., converging
northward. The formation is clay slate on the foot-wall, and amphib-
olite schist on the hanging-wall. A banded vein occurs at the contact
of these formations, and a brecciated gray ore in the schistose portion.
Idle. B. K. Thorn of San Andreas, owner.

Demarest Mine. — This is 6 miles south of San Andreas, near the road
to Copperopolis. It is an old mine, which has been reopened since the
last report was issued. An inclined shaft has been sunk to a depth of
640 feet, and still sinking in April, 1900. It has a steam hoist and a
5-stamp mill. A short shoot of very good rock has been encountered in
the several levels of this mine, the formation in which it occurs being
diabase. A gouge usually accompanies the vein. This, in the northern
end of the mine, lies on the hanging-wall side of the quartz, on the 300-
foot level. Some distance south of the shaft there is a sudden flexure
of the walls of the vein, the gouge passing over to the foot- wall side of the
quartz. A second shoot of what is said to be good ore is known to exist
under the bed of the creek south of the main workings, but this has not

as yet been reached under ground. There are 18 men employed. The

Demarest Gold Mining Company of Angels, owners. T. H. FuUen of
Altaville, superintendent.

The Ford Mine. — It is three fourths of a mile east of the Mother Lode,
at San Andreas. The rock formation is chiefly chlorite schist, resulting
from the alteration of diorite and possibly also diabase. The foot-wall
(west) of the mineral belt of the Ford Mine is a hard, dense, quartz
schist, often impregnated with iron sulphide (pyrite), which is usually
auriferous, though at this place to a limited extent. The hanging-wall
country is greenstone schist, not materially different from that exposed
in the mine workings. There are two other rocks in the mine which lie
near the foot-wall. These are, first, a hard, tough, dark-green rock
(No. 23), composed of an aggregate of talc scales, often schistose, and in
an extreme state of alteration passes over to talc schist and massive

108 CALIFORNIA STATE MINING BUREAU.

steatite; second, a dolomitic rock (magnesian limestone), which is also
much altered and passes over to talc schist.* This rock greatly
resembles the ankerite of the Gold Belt, but shows no green mariposite.
These two rocks are of structural importance only, as no ore has as yet
been found in them. The Ford Mine may be described as a mineral
belt consisting chiefly of chloritic and talcose schists, lying upon a quartz
schist foot-wall, and having a hanging-wall of diorite, locally found
altered into chlorite schist. The included belt is about 100 feet in width,
and within it occurs large lens-like masses of quartz, and also vein-like
sheets of quartz. The former are often found mixed with a gray rock
which is a portion of the greenstone. These masses of quartz and frag-
mentary greenstone are a common feature of many important mines of
the California Gold Belt, and often constitute large and valuable
deposits of gold ore; but there are many millions of tons of rock
seemingly identical, which are of little or no commercial value, owing
to the extremely low tenor in gold. In the Ford Mine, as elsewhere,
these large deposits contain a variable percentage of iron sulphide
(pyrite). The large quartz bodies range from a foot or two to nearly
100 feet in width. There is a small vein near the foot-wall side which
appears to possess elements of value, but to what extent it is impossible
to say. This vein has a strike west of north, dipping easterly with the
main quartz bodies, but not connected with them down to the 400-foot
level. This vein and the small feeders of quartz running into it have
produced rock of phenomenal richness. It also contains considerable
quantities of petzite (gold-lead-silver-bearing tellurium). The gold and
tellurium occur, in this small vein and the stringers leading into it, in
what is known as an ore-shoot — that is, the distribution of the gold in
the vein appears to be chiefly confined to a limited area, apparently 30
or 40 feet in length, and having a trend along the vein downward to the
north at about 35 degrees from the horizontal. Gold has been found
nowhere else in this vein than along the shoot as described. A persistent
characteristic of this vein is the occurrence of thin films of iron sulphide
incrusting the cracks and seams of the quartz. In this vein gold was
found on the surface; south of the shaft on and above the 100-foot
level; in the shaft at about the 100-foot level; in a winze sunk on this
level north of the shaft; and in a drift north of the shaft on the 300-
foot level, where, I am informed, a $900 pocket was found. The repeated
occurrence of the gold and tellurium at the points indicated, shows
clearly the downward and northward trend of the ore-shoot. The mine
is equipped with a steam hoist and 10-stamp mill. The mine is
developed to a depth of 700 feet, and I am informed that the shaft is to

*An investigation of similar rocks, near Forest Hill, Placer County, has led me to
believe that the two rocks here described represent different stages in the alteration of
the same rock.

THE MOTHER LODE REGION — CALAVERAS COUNTY. 109

be sunk 200 feet more. There are 10 men employed. Ford Mining

Company of San Andreas, owners. D. Gutmann of San Andreas,
manager.

Angels Mine. — Is in the town of Angels, and is the second mine north
of the Utica, and presumably on the same vein. It comprises a group
of five fractional claims. The mine was worked, extensively in former
years, but until a year or more since has remained idle for many years.
A vertical shaft has been sunk 350 feet, and three levels opened on a
zone of amphibolite schist and quartz containing gold and auriferous
iron sulphide. Only the north end of the property is in operation. The
ore is crushed in a custom mill. The mine is equipped with a steam

hoist. There are 40 men employed; 24 in the mine. Angels Quartz

Mining Company of San Francisco, owners. O. S. Buckbee of Angels,
superintendent.

Lightner Mine. — In the town of Angels, the first extension north of
the Utica, and on the same vein. The Lightner is a fractional claim,
on which a shaft has been sunk to a depth of 447 feet, and five levels
opened. The vein consists of a zone of amphibolite schist and quartz,
ranging from 10 to 90 feet in width, and is essentially the same as the
Utica Mine, geologically. The gray, granular dike rock, characteristic
of the Utica-Stickle Mine, which forms large masses of the best ore of
that property, is also prominent in the Lightner. The mine is sub-
stantially timbered with a modification of the square-set system. The
property has a good hoisting plant, air-compressors, electric machinery,
and a 40-stamp mill. The mill is operated by electricity, the hoist by

steam. There are 50 men employed. The Lightner Gold Mining

Company of Stockton, owners. V. W. Miller of Angels, superintendent.

TJie Lightner Mill. — This is a modern mill of 40 stamps, run under
the direction of J. E. Reaves. It originally contained 20 stamps, but
was enlarged to 40. Twenty of the stamps weigh, when new, 955
pounds, and twenty weigh 750 pounds. The height of drop of the
heavier stamps is 7 inches; that of the lighter, 7^ inches. The number
of drops is about 100 per minute; the height of discharge, 8^ to 9
inches. A No. 1 punched tin screen is used. The capacity under these
conditions is about 5 tons per stamp daily (by car measurement). This
tonnage is probably due to the peculiar character of the ore, which con-
sists of a considerable quantity of chloritic schist and calcite, and sharp
grains of quartz, which pulverize readily, the stamp cutting the softer
material rapidly. The gold is mostly caught inside the battery. The
apron plates are 24 by 48 inches; the sluice plates are divided and are
20 inches by 20 feet. No traps of any kind are in use. There are 20
Frue vanners — twelve 4-foot and eight 6-foot machines. The ore con-
tains about 2 per cent of pyrite. The pulp from the batteries is divided,

110

CALIFORNIA STATE MINING BURP:AU.

hut not sized, before going to the vanners. The speed of the concen-
trating machines is controlled by means of a cone pulley. An experi-
ment was made on a lower discharge (at 7-| inches), which resulted in
scouring of the inside plates. This was discontinued for the higher

PocKEtT in /^ILL c>CREE:N

LiGHTNE-R Mill,

Angels, California.

P = Pocke-t: W. ' Iron WcA^cs.

Fig. 32.

discharges now in use. Chrome shoes and white iron dies are in use in
this mill. The latter last five months, crushing 750 tons of ore. The
concentrates at this mill are worked by chlorination at the Utica plant.
An ingenious screen has been invented by Mr. Reaves, which is illus-
trated in the accompanying sketch (Fig, 32).
The screen is fitted with two pockets at the
front, and these may be opened at will, and
chips or other foreign matter removed by
inserting the hand. The method of securing
the screen to the frame is shown in the illus-
tration. (Fig. 33 is an
Chuck Block illustration of the Lightner
, . . chuck-block, with iron rods

to protect the plate from
R.R. lrbr-\l^ods. scouring.)

Utica-SticJde Mine. — It is
at Angels. Since the last report, a vertical
shaft has been sunk to a depth of 1370 feet.
This shaft is located south and east of the old
shafts, and is in the hanging-wall schists. It
is substantially timbered throughout with heavy sets, and a large, expen-
sive hoisting plant has been installed. This machinery sets on concrete
foundations, which were constructed in the most substantial manner.
For more than a year the lower levels have been flooded in the southern

Fig. 33.

THE MOTHER LODE REGION — CALAVERAS COUNTY. Ill

part of the property. When the new vertical shaft was completed it
was found that the hoisting plant, with the use of which the shaft had
been sunk, was incapable of doing more than handle the water coming
in at that point, and it was determined to discontinue mining operations
in the lowest levels until such time as it became possible to put in a
heavy plant that would economically handle both the water and ore.

Theorder for the new machinery was promptly placed,and it should have
been in position in August, 1899, but owing to the inability of the makers,
the Union Iron Works of San Francisco, to furnish necessary material,
due to scarcity of iron, the great hoist was not ready for operation until
early in September, 1900. During the past year or more all mining
operations in this property have been confined to the upper levels of the
mine.

The lower levels will now be unwatered and the large new ore-bodies
discovered prior to the flooding of this portion of the mine will be worked
vigorously. This property also includes the Madison and Gold Cliff
mines, situated half a mile west of the Utica-Stickle group.

An extensive electric installation has been added to the Utica Com-
pany's plant. The generators are located above Murphys, on the com-
pany's ditch-line. The power is distributed to their various properties at
Angels, where they also sell power and light the town. The Utica-
Stickle and Gold Cliff mills are operated by this power, and also the
mill of the Lightner Company, adjoining the Utica.

Gold Cliff Mine. — This is one of the Utica group, and is being opera-
ted through an inclined shaft 600 feet deep, sunk from the level of the
old open cut. Four levels have been opened in this mine. The vein
is found in a broad zone of amphibolite schist, with serpentine on the
hanging-wall. The ore occurs in several zones, which overlap in the
foot-wall going north. On the 400-foot level north of the shaft, the vein
splits, being separated by a horse of diabase. Whether or not these
diverging veins will re-unite is not known. The ore from the Gold Cliff
Mine is crushed in the 40-stamp Madison mill. At the Utica Mine there
is a 60-stamp mill, and the Stickle also has a 60-stamp mill, making a
total of 160 stamps on the consolidated properties. There are 420 men
employed in and about these works, distributed as follows: Utica, 125;
Stickle, 90; Gold Cliff, 40; the mills, 25; chlorination and cyanide

plant, 30; outside, 110. Hayward, Lane, and Hobart Estate of San

Francisco, owners. J. L. Shinn, manager. The Madison' Mine has been
idle for some time.

Utica Mills. — The three Utica mills are under the superintendence of
W. J. Loring. The stamps of the Utica mills weigh 780 pounds; those
of the Stickle, 835 pounds; and of the Madison, 920 pounds. These
drop from 7 to 8 inches 105 to 107 times a minute. The height of dis-

112 CALIFORNIA STATE MINING BUREAU.

charge in the Utica mill is 10 inches; Stickle mill, 7 inches; Madison, 5
inches. The Utica and Stickle mills are provided with No. 1 punched
tin screens, and the Madison with No. 2. The capacity of these several
mills will average about 5 tons per stamp daily. With the heavier
stamps and low discharge of the Madison mill, it would be expected that
the capacity of that mill would exceed that of the Utica or Stickle, but
the Gold Cliff rock is much harder than that of the other mines.

Mr. Loring gives the following description of the Utica 60-stamp mill,
and the daily routine work, together with method of making monthly
clean-up, etc.:

The rock, as hoisted from the mines, is dumped at the head of the
shaft over a grizzly made of 3-inch round iron bars, 10 feet long, placed
If inches apart, and set at an inclination of 40 degrees. The bars are
supported at each end by an iron casting, with recesses to receive them.
Old stamp stems are used in the grizzly. At the lower end of the grizzly
the rock passes to a Blake crusher 10 x 16 inches, being fed by gravity.
One crusher of this size handles all the rock for the 60-stamp mill.
One man is employed here on each ten-hour shift.

The crusher and grizzly set over a 50-ton bin, from which ore is con-
veyed to three bins of 200 tons capacity each in the mill by means of
a dump car. The bins discharge into Challenge feeders. In the Utica
mill they have made a practice of keeping on hand a new cam shaft
with ten cams in place, which, in event of breaking the shaft, may at
once take the place of the broken shaft. In case of such diflficulty,
much time is saved by this arrangement. The discharge in the batteries
is 10 inches high; three differential chuck-blocks are in use, keeping
the discharge as nearly uniform as possible. Manganese steel shoes are
used" these are 10 inches long, 8^ inches in diameter of face, and weigh,
new 177 pounds; when worn out, they weigh but 28 pounds; their life
is about 296 days. The dies are made of hard iron, and last 120 days;
they are 5 inches high, 8f inches in diameter of face, and 9^x9^
inches base area; they weigh 84 pounds, and after using, about one half
of this. Round needle punched tin screens are used in sheets 10x14
inches; No. 1, or 30-mesh, has been found to give the best satisfaction,
and lasts from 15 to 20 days. Before using, these are burned over a
moderate fire of charcoal, for the purpose of removing the tin, to pre-
vent amalgamation of the tin. This anneals the metal, and makes it a
very tough, durable screen. A splashboard made of 1 x 12 inch clear
pine, having the full width of the screen, is suspended to the screen
frame by two eyestraps riveted to each end of the board and two hooks
screwed to the screen frame. A strip of canvas 6 inches wide is tacked
to the lower end of the board, to confine the splash to the apron.
Underneath the screen is bolted an iron apron, which constitutes a por-
tion of the mortar, and being an inch below the lip of the mortar,

«|^.<^'>,- -.i -rf:.

''i^l

••»■•»>

! A

■•jSfsmn'*^"^'-

North Shaft and Mill, Utica Mine, Calaveras County.

The Keystone Mine and Mill, Amador City.

THE MOTHER LODE REGION — CALAVERAS COUNTY. 113

permits the insertion of a rough board 1x12 inches, which lies flush
with the upper edge of the lip of the mortar. Upon this the pulp from
the screen falls, and it is considered a good amalgamator. After being
in use a short time, it amalgamates quickly, but does not stand the jar
as well as the copper plate. A splashboard of this kind can be cleaned
in one eighth of the time required to clean a copper plate. The board
is protected by a 2x6 inch board, extending across the apron, and
having a |-inch hole bored at each end to receive two hooks fastened to
the battery posts. Four inches below the board, on the apron, runs a
trough in which are two apertures 3 inches square, through which the
pulp passes to a copper plate 5 inches wide, with a pitch toward the
mortar, whence it passes to the sluice plates, 2 feet wide and 22 feet
long, covered with yVi^ich copper plates set on a grade of 2 inches to
the foot. Each battery has two separate runs of these plates, set inde-
pendently, provided with wedges to adjust the grade. Before putting
on the plates, the tables are dressed down in the center about y^ inch
for the full length. This causes the pulp to run in angular waves
across the plate. If the tables are left plain without the center depres-
sion, it is a difficult matter to cause the pulp to be evenly distributed
over the plate, as it usually flows to one side or the other. The first
8 feet of plate at the upper end of each sluice is raw copper, the remain-
ing 14 feet being plated with 24 ounces of silver to the square foot.
The plating is done in the works of the company. The plates are
cleaned every morning.

A plug of soft wood is driven into one of the 3-inch holes of the cast-
iron aprons previously described, causing the pulp to run through the
trough and out of the other 3-inch hole discharging on the other plate.
The plate to be dressed is first washed with clean water to remove sand,
then sprinkled with quicksilver, and rubbed vigorously with a whisk-
broom for the purpose of loosening the amalgam. About once a week
a weak solution of cyanide of potassium is used in dressing the plate.
This operation must be done with care, as the application of too much
cyanide causes the plates to become glazed and brittle, when they are
no longer fit for the use for which they are intended. After the plates
have been thoroughly rubbed with a whisk- broom, they are rubbed down-
ward with a piece of pure India rubber i inch thick, 4 by 7 inches in
area. The amalgam is then taken up, together with the sulphides which
may have adhered to the plates during the twenty-four hours. The
plate is then lightly sprinkled with quicksilver at the head, and lightly
brushed with a whisk-broom its full length. The last plate is always
brushed upward from the lower end, to place any amalgam which should
be hanging to the lower edge of the plate in a position where it may be
seen and collected. By this method, two men can dress twenty-four
8 — MB

114 ' CALIFORNIA STATE MINING BUREAU.

sluices, 22 feet in length by 2 feet wide, in from one and a half to
two hours.

For the purpose of saving the rich sulphurets which have adhered to
the plates, and which are often worth $10 per pound, the amalgam col-
lected each morning is cleaned in a tank used for that purpose only.
At the end of the month this tank is cleaned out and the sulphurets
are charged with 25 pounds of quicksilver, into an amalgamating barrel
of 40 inches diameter and 48 inches long. This revolves for eight
hours, at 14 revolutions per minute. The charge is taken out through
the head with a dipper, is panned and settled. The amalgam is cleaned
in the usual way, and the sulphurets sent to the chlorination works in
a wooden bucket. At the lower end of the sluices is a tail-box, having
the width of a double sluice, with a drop of 3-^ inches, and a width of 5
inches on the bottom. This box has a wing its full length, with a pitch of
about 45 degrees toward the sluice plates, and extends to within ^ inch
of the bottom of the box. The wing causes the pulp to pass under it
and keep the box clear at the bottom, catching any free quicksilver.
From this opening extends a sluice 12 inches wide and 8 feet long, the
upper end of which is provided with 4 x ^ inch riffles 2 inches apart,
while below the riffles are 6 feet of silver-plated copper plates. This
box has a grade of | inch to the foot, and from it the tailings pass to the
concentrators.

Each battery has three concentrators. There are in use in the several
mills of the company fifty-four 4-foot Frue, six 4-foot Union, and six-
teen 3 foot 10 inches Tulloch machines. A series of comparative tests
was made some time since, which showed little difference in the value
of the tailings passing the machines. Mr. Loring made special experi-
ment with several of the Frue machines. The machine has a shaking-
frame 12 feet long and 4 feet wide. The back roller was dropped 3
inches by putting a block of wood between the side rail and the bearing
that supports the roller. Then a number of small rollers which carry
the belt were taken out, reducing the total length of the concentrator to
8 feet from the center of the head roller to the center of the small roller.
The belt from the small roller to the back roller had so much grade that
nothing was saved on it, so that by this arrangement of the concentra-
tors the effect was the same as though the machines were but 8 feet long.
Tailings assays showed as follows:

From the altered machine, 4x8 feet $0 33 per ton.

From the unaltered machine, 4x12 feet 41 per ton.

This shows a saving of 8 cents per ton in favor of the short concen-
trator. This being the case, it would appear that a 12-foot machine is
unnecessarily long. On each concentrator is a discharge, which deposits
the sulphurets in a box directl}' under the head roller of the machine,
and from this box the concentrated sulphurets are removed daily. A

THE MOTHER LODE REGION — CALAVERAS COUNTY. 115

car holding 900 pounds is used to convey them to the dump-house.
Two samples are taken from each car with a 15-inch sampling iron,
and after all concentrates for the day have been taken out and sampled,
the aggregate sample is sent to the assay office, together with the aggre-
gate of the samples of tailings, taken every three hours. These samples
are assayed every day, and a record kept. The tailings from the con-
centrator run through a flume three fourths of a mile long, and are
passed over a slimes plant of the Gates type. The concentrates from
the slimes plant are conveyed by wagon to the chlorination works,
where they are worked in a cyanide plant attached to that department
of the works.

After a run of fifteen or twenty days, depending on the character of
the ore, a general clean-up of the mills is made, as follows: The feed
is shut off from three batteries until they have been "pounded out";
the stamps are then hung up, the water shut off, and two rectangular
pans, 15x14 inches in area, 3 inches deep on one side and 2 inches on
the other, are placed in front of each battery, the low side of each being
slipped under one of the holes in the apron. These pans are made in this
form to keep the upper edge as nearly level as possible when sitting on
an inclined plane. The amalgam adhering to the screen frame is taken
off with a scraper, and deposited in a gold-pan. The screen frame is
then removed and washed; afterwards the chuck-block is taken out and
placed in the clean-up room, to be cleaned; the wooden apron is then
scraped and the amalgam put into a bucket; the coarse battery sands are
then shoveled into a box provided for that purpose, and the pans with
the cleanings from the screen frame are successively put under each
stamp, which is thoroughly cleaned of any amalgam found in key-ways
or between the boss-head and shoe, i^fter each stamp has been thor-
oughly cleaned in this way, the amalgam is taken to the clean-up room,
a check being kept on the weight of that from each battery separately.
The di6s are then removed and washed on the apron, and the batteries
cleaned out, all the hard sand that has accumulated around the dies
being put in an amalgamating barrel. After the mortar has been
thoroughly cleaned, about half an inch of sand is spread on the bottom
of the mortar, the dies are returned to their respective places, coarse
sand packed in, and the chuck- block, which has been cleaned, replaced;
the screen is replaced and keyed; the apron washed, and everything
cleaned, down to the rectangular pans previously mentioned. These
pans, and the buckets used around the battery, are washed into the
amalgamating barrel. By the time the clean-up man has completed
washing the buckets and pans, the man employed in looking after the
self-feeders has started the cleaned-up battery, and has its neighbor
ready to be opened. Three men on the batteries and three men in the
clean-up room can clean up twelve batteries in three hours. When the

116 CALIFORNIA STATE MINING BUREAU.

battery is first hung up, the small spreader plates are taken to the
clean-up room, and the amalgam obtained is dropped into a tank,
which, after the clean-up, is cleaned out and charged with other material
in the amalgamating barrel.

After the mill has been cleaned up, 150 pounds of quicksilver is put
into the barrel, with sufficient water to give a depth of 12 inches over
the charge. The barrel is then closed, locked and sealed, and the belt
put on, which drives the barrel at 14 revolutions per minute. This
charge is run 30 to 48 hours. Underneath the barrel is a tank of equal
capacity, from whence a sluice 22 feet long and 12 inches wide with a
grade of 1^ inches to the foot, provided with silvered copper plates, con-
veys the pulp and water to either of two settling tanks as desired.
When the barrel has run its full time, it is stopped with the head up,
the head removed, and a stream of clear water under high pressure
turned in, causing the slimes to come to the top of the barrel, overflow,
and fall into the tank beneath, from which they pass through the sluice
into a tank of 2000 gallons capacity. When the slimes have been
washed out, the water is shut off. A bucket is set under the If-inch
plug-hole in the barrel, and the charge is drawn. The quicksilver first
flows out, falling to the bottom of the bucket. A stream of water is
kept running through the barrel to wash the sand through the discharge
hole, and the bucket is thoroughly scraped, so that the sand will over-
flow, leaving the amalgam in the bottom, the "iron" next, and the sand
on top. The iron is taken out as it accumulates, and after it has all
been collected, it is screened through a ^-inch screen and the screenings
panned in the clean-up tank. The result is put back into the amalga-
mating barrel at the next regular clean-up. The amalgam from the barrel
is thoroughly cleaned and squeezed through white drilling. The
amalgam balls weigh from 8 to 12 pounds, and retort about 38 per cent
gold. The day before the buckets are to be cleaned, the accumulations
on the sluice plates are scraped off with steel scrapers made of old files
turned at one end about 2 inches, and ground to a sharp edge. The first
8 feet of raw plate is scraped in this way, leaving the 14 feet of silvered
plate to run six months more without scraping. Great care must be
taken in scraping silvered plates, as the silver cuts easily, spoiling the
plate and making low-grade bullion. The amalgam thus collected is
put in a small amalgamating barrel 15 inches in diameter and 24
inches long, which is run 28 revolutions a minute, quicksilver being
added, with enough water to make a thin paste of the charge. The
charge is run for twenty-four hours, when it is drawn off in a bucket and
cleaned in the usual way, the sulphurets being saved in the cleaning
tank previously described. This amalgam yields from 28 to 30 per cent
gold.

Quicksilver is fed to the battery every hour; the amount being

Saved

THE MOTHER LODE REGION— CALAVERAS COUNTY. 117

regulated by the value of the ore, and this must be judged by the amal-
gamator from examination of the board directly under the splash of the
battery, where the pulp first falls from the screen. Every ounce of
quicksilver that is fed into the battery is weighed and recorded at the
end of each shift, and at the end of the run the amount of quicksilver
thus fed furnishes a basis for calculating the probable result of the
clean-up before it is made. The retorts are lined with oak wood ashes,
free from dirt; the ashes are sifted through a 30-mesh screen, and made
into a paste Avith water; with this paste, the trays and retorts are lined,
and the head thickly sealed. The ashes do not shrink like clay, to
which it is superior in many ways.

The mortars in the Utica mill are of an old-fashioned type, not
having been provided with liners. After being in use several years, it
was found necessary to do something if the life of the mortars was to be
prolonged, as the ends were badly worn just above the dies The stamps
were set 10 inches between centers, using 8^-inch shoes, leaving a space
of 14 inches between each two shoes. The 9-inch dies up to that
time had a life of 59 days, and the chrome steel shoes were being used
191 days. In order to line these mortars, Mr. Loring reset the stamps,
using a guide with 9^ inches between centers, and leaving | inch between
stamps. In this manner 1^ inches were gained at each end of the
mortars, allowing room for an end liner, which served to key the front
and back liners. The back was filled with wood, carefully fitted in
place with the liner, saving considerable weight of unnecessary iron.
The back liner is 13 inches high, and stands at an angle of 77-2 degrees,
the foot being 1^ inches from the base of the die. These dies are made
with 8|-inch face, while the shoes have but 8^-inch face. It is claimed
by Mr. Loring to give better results than when both shoe and die are of
the same diameter.

The chuck-blocks are made of wood covered with copper, | inch thick
and 8 inches wide, the full length of the battery. In the center the
copper is bent to fit the wooden block, the upper half being set at an
angle of 45 degrees, the lower half standing vertically. At the lower
edge of the block, and projecting -^ inch over the copper, is bolted a ^x 1
inch iron strap the full length of the copper. At the bend in the copper^
3Y about 2 inches above the bottom iron, is bolted a second iron strap,

X I inch, the full length. The bolts holding these iron straps are
countersunk, and the iron bars act as a protection for the amalgam
which accumulates between them, and it has also been found to prevent
Lhe scouring of the upper section of the plate. There are used 8^
gallons of water per battery of 5 stamps per minute, and in addition
li gallons per minute outside for each battery.

All chips, shoe wedges, and other wood used about the mill, are
saved and burned in a 5 X 8-foot furnace constructed for that purpose.

118 CALIFORNIA STATE MINING BUREAU.

The furnace has a cement floor; above it are placed grate bars to the
full size of the furnace. The furnace measures from cement floor to top
of bars, 15 inches; from the top of bars to the top of the arch, 5 feet;
at the top of the furnace is a charging hopper made of cast-iron, with
a door to fit it. When the charge has been burned, the ashes are
removed and screened to remove nails, etc., that may be in the charge.
The ashes are put in the amalgamating barrel with 10 pounds of quick-
silver, and ground for six hours sharp, as a longer time would probably
cause the charge to " flour." From 6 ounces to 2 pounds of amalgam is
obtained by this method every month. All the cleanings from the mill
are put into this barrel and ground for such time as the case may
require. In this way many thousands of dollars are saved around a
large plant, by care. The amalgam from the chuck-blocks is ground in
an iron mortar 12 inches in diameter, the muller of which has a con-
nection made in such a way that it can be stopped or lifted as desired.
It will grind a charge of 14 pounds, and has a speed of 65 revolutions
per minute. The labor employed in the mill is as follows: One man to
each shift of twelve hours, whose duty it is to look after the feeding of
the batteries; one night amalgamator, who attends to the amalgamating
and looks after the mill generally; one concentrator man on each twelve-
hour shift, who attends to 36 concentrators; one day amalgamator and
helper, who attend to the amalgamating and general repairs about the
mill; one superintendent, who has charge of everything connected with
the mills and plating works; thus seven men, besides the superintendent,
operate a 60-8tamp mill. Owing to the fact that the company own their
power, against which they make no charge for the plant or deterioration,
the cost of milling at the Utica mills is very low, being, before the recent

rise in the price of iron, about 14 cents per ton. W. J. Loring,

superintendent, Utica Mills.

The Utica Chlorination Works. — This plant consists of seven furnaces,
having a daily capacity of 29 tons. F. C. Beedle is superintendent.
Four of the furnaces are in constant operation. They are 72 x 13 feet,
and have a capacity of 4| tons each daily. The material treated in these
furnaces is iron sulphide, concentrated from the Utica-Stickle and Gold
Cliff ores. The tanks are made of redwood held by |-inch round iron
rods, each in three sections and secured with screw clamps. This
method of clamping tanks draws the staves evenly, secures great firm-
ness, and renders the tanks perfectly water-tight. The covers of the
tanks are no longer "luted" on as formerly, but are provided with a
downwardly projecting flange, which drops in an annular trough
encircling the tank and filled with water. The accompanying diagram
(Fig. 34) illustrates this construction of the air-tight water joint. The i
covers are raised by means of a chain block suspended from an over
head traveler. The tanks have a capacity of 5 tons each. The pipes

THE MOTHER LODE REGION — CALAVERAS COUNTY.

119

from the chlorine gas generators, which latter are very large, are so
arranged that when the gas is turned into No. 1 tank, having permeated
the ore below, it passes from the top of No. 1 tank into the bottom of
No. 2, so that there is no waste of gas. In generating gas, 100 pounds
of salt and 90 pounds of black oxide of manganese are used. To this,
sulphuric acid is automatically added, until it ceases to- evolve gas.
Liquid chlorine was at one time tried in these works, but Mr. Beedle
said it was found to cost twice as much as making gas by the above
described method, though otherwise satisfactory. The ore is introduced
to the reverberatory furnaces containing 5 to 10 per cent moisture, in a
charge of 2600 pounds. It is spread in a 2-inch layer on the first

EXPLANATIOM.

Staves forming vai.

Outside ring, encircling vat.

Space filled wiib water.

Plange extending downward from
cover.

Iron Hoop.
Tilling piece.

Section of Cover and 1op of Vaf, Cf7lorination Works,
Utica Mine: /Angels, Cat.

showing air -iT^ht vVater loLnt. —

Fig. 34.

hearth. After two hours it is stirred, and later it is restirred three
times before being raked forward to the second hearth. On the second
hearth, 40 pounds of salt are added to the charge; on the third hearth,
the ore, having been thoroughly roasted, is withdrawn from the furnace,
cooled and charged into leaching-vats. One and one-quarter cords of
wood are required to roast 5 tons of ore.

Utica Cyanide Plant. — In this plant 8800 pounds of slimes obtained
from the canvas plant are treated in eight hours. This is charged in
steel tanks, and agitated 6 hours with a 5 per cent solution of potassium
cyanide. The pulp is discharged into a vacuum filter, and is first
washed with sump solution, and later with fresh water. The results
are said to be entirely satisfactory. The auro-cyanides are precipitated
on zinc shavings.

Bovee Mine. — This property adjoins the Fox or Angels Mine on the

north, at Angels. It has been idle for many years. The Marshall

Mining Company, owners. E. P. Lynch of Angels, agent.

120 CALIFORNIA STATE MINING BUREAU.

Perlina Mine. — At Altaville, northeast of the Angels Mine. It has
an inclined shaft 75 feet deep, from which drifts have been run on the
vein. The property has been superficially worked for years, the ore
being crushed in a 4-stamp mill. The vein has never been cross-cut,
and its width is unknown. As far as known at this writing, the vein
has a width of from 4 to 12 feet, between two gouge seams. The
formation is diabase and amphibolite schist. There are 3 men em-
ployed. J. G. Maltman of Angels, owner.

Great Western Mine. — At Altaville. It has a vertical shaft 220 feet
deep, with drifts at 50, 100, and 200 feet south of the shaft, no work of
consequence having been done to the northward. There is a stope at
the 50 foot level and one at the 100-foot level. On the latter level, it is
said the vein is from 8 to 20 feet in width. The hoisting machinery has

been removed and the mine is idle. Seifert & Baumhogger of Angels,

owners.

St. Lawrence Mine (Bruner or Bald Hill). — This mine has been
reopened since the last report, and an inclined shaft sunk 400 feet at
an angle of 64 degrees; there is a level at 100 feet and another at 400
feet. An open cut on the surface exposes a shoot of ore 80 feet in length,
which was worked down to a depth of 60 feet many years ago. The
trend of this shoot is to the south, at an angle of 40 degrees; two other
shoots are known to the northward. The formation is diabase and
chlorite schist. The vein consists of a mixture of quartz and diabase,
impregnated with auriferous iron sulphides and free gold. The mine is
equipped with a steam hoist, but has no mill. The south drift at the
400-foot level had not reached the ore-shoot at the time of my visit, but

drifting was in progress. St. Lawrence Gold Mining Company of

Hanford, Cal., owners. A. J. Cameron of Angels, superintendent.

Bolytho Mine. — This is 1 mile south of Angels, and has been men-
tioned in previous reports. It was originally worked as a pocket mine,
and as such produced several thousand dollars in gold. Expensive
development was then undertaken, with a view to working it as a
milling proposition, but up to this time the experience of the operators
has been rather unsatisfactory. The last work performed was the sink-
ing of a vertical shaft to a depth of 300 feet; this shaft passed through
a succession of formations — diabase tuff and tufaceous slate, character-
istic of the Gold Belt, being most prominent. These formations are
intruded by a dike of straw-colored rock, which is identical with the
intrusive rock found in the Utica-Stickle, Gold Cliff, and other important
mines in this section. The dike is from 30 to 40 feet wide, and carries
much finely disseminated iron sulphide, which is doubtless auriferous,
but to what extent is not known by the management, as no attention
was paid to it, for the reason that it was not massive quartz. It is the

THE MOTHER LODE REGION — CALAVERAS COUNTY. 121

intention of the company to cross-cut from the bottom of the shaft to
the eastward and again intersect the dike, which is, undoubtedly, what-
ever its value may be, the main ore zone of the mine. When this is
done, long drifts will be run for the purpose of prospecting. Geolog-
ically, this mine possesses many of the features common to the best
mines of this section. In addition to this shaft, an inclined shaft has
been sunk 300 feet on a west vein, and thousands of feet of drifting and
cross-cutting have been done in the upper portions of the mine in search
of pockets and pay rock. The vertical shaft is equipped with a steam
hoist. Bolytho Mining Company, Appraiser's Building, San Fran-
cisco, owners. E. P. Lynch of Angels, superintendent.

Big Bonanza Mine (Harris or Oriole).— It is 1 mile south of Angels,
and has been developed by a vertical shaft, which was 425 feet in depth
May 1, 1900. A level has been run at 130 feet, 60 feet southeast, and
another at 200 feet. The formation in which this mine occurs is augite
diorite, in which occur fine-grained phenocrysts of hornblende and
augite. This rock near the vein is altered to chlorite schist. The vein
consists of a zone of quartz and schistose rock, dipping 75 to 80 degrees
to the eastward. The mine is equipped with a substantial steam hoist,
but has no mill. There are 15 men employed. Sinking is in progress.
It has been recently reported that 30 feet of ore has been developed on
the 400-foot level, 5 feet of which is high grade. Oriole Mining Com-
pany of Stockton, owners. John H. Heard of Angels, superintendent.

Drale Properties {Ltd.). — These are a mile southeast of Angels. Two
shafts have been sunk— one 900 feet, the other 300 feet— vertically for
the purpose of prospecting. The formation is diabase and black
tufaceous slate, the latter being cut by a small dike with quartz and

pyrite. Idle. Drake Properties (Ltd.) of London, owners. F. J.

Solinsky of San Andreas, agent.

Tulloch Mine.— It is 2^ miles south of Angels. After a long idleness
it has been reopened and sinking is in progress in the shaft, which Sep-
tember 1st was down 250 feet. Steam hoist. There are 12 men
employed. Mr. Blevin of Angels, superintendent.

Relief Mine. — It is 1 mile south of Angels. It has a cross-cut tunnel
165 feet long, and a winze sunk on a zone of schist 90 feet below the

tunnel level. The mine has no machinery. Idle. Bonded to San

Francisco company. Mr. Hogarth of Angels, owner.

Melones Consolidated Mines. — This group of mines is on Carson Hill,
reaching from the summit of that eminence to the Stanislaus River,
and embraces seven claims extending along the lode for a distance of a
mile. The claims are the Reserve, Last Chance, Melones, Enterprise,
Mineral Mountain, Keystone, and Stanislaus. These mines were among
the first worked in the county, and the several claims have been

122 CALIFORNIA STATE MINING BUREAU.

developed to depths varying from superficial, though large cuts, to
shafts 300 feet or thereabouts in depth. The development undertaken
by the present owners consists in an extension of the South Carolina
tunnel. (This property adjoins the Melones Consolidated on the east.)
It was run through the Enterprise and Reserve ground under the large
open cuts on the surface, and connection established. It is 621 feet
below the collar of the Reserve shaft. This development has exposed
large veins of ankerite and quartz with amphibolite schist, all of which
is gold-bearing, with auriferous sulphides. To what extent these great
veins are auriferous is of course a very important factor, viewed from
the commercial standpoint. The values vary greatly, ranging from
many thousands of dollars per ton to a mere trace of gold. Large
samples taken systematically from cross-cuts on the veins show values
varying from $1.50 to about $9, the greater portion running from $2.50
to $3.50 per ton, though some portions average better than this, accord-
ing to statements made by the management. A new tunnel (designated
as No. 3), 6 feet 6 inches by 9 feet clear, was started to run under the
South Carolina tunnel about 200 feet lower. This tunnel is now in about
3500 feet, and judging from the character of the formation passed through
in the last 100 feet is nearing the vein. The tunnel cuts diagonally
across the formation, and is being driven through the foot-wall country-
It is perfectly straight, has a double track throughout, and is a credit-
able piece of mine engineering. Machine drills are in use, the com-
pressors being situated near the mouth of the tunnel. There are still
several hundred feet to run before this tunnel reaches a point beneath a
winze sunk from the South Carolina tunnel. A raise of 65 feet from
the new tunnel will make this connection at a point 1000 feet below the
cropping on the summit of Carson Hill. The grade for a 120-stamp
mill has been completed, and a large amount of machinery is on the
mill site. The first attempt to construct a dam across the Stanislaus
for the purpose of furnishing power for this property was a failure, and
a new site was chosen a few feet higher up the stream. This is about 2^
miles above Robinson's Ferry. The dam is being put in at this writing
(September 1, 1900), and it is stated that no obstacles to its successful
construction have been encountered thus far. The water diverted by the
dam will be conducted by ditch and flume to a point opposite the mill
site, and it is calculated to furnish power for the entire plant. This is
one of the largest mining operations in the State, but much still remains

to be done before it can be placed on an operating basis. Melones

Consolidated Mining Company of Boston, owners. W. C. Ralston of
Robinson's Ferry, manager.

Last Chance Mine. — Near the town of Angels, on the southern limits.
Nothing has been done here since the last report. It has an inclined
shaft 73 feet in depth. G. C. Tryon of Angels, owner.

'

THE MOTHER LODE REGION — CALAVERAS COUNTY. 123

San Justo {Carson Creek) Mine. — The work in progress May 1, 1900,
is in a south drift on the 250-foot level, where a new ore-shoot has been
discovered. The mill, which had long been idle, was started up May
Ist, and the chlorination works one month later. The mill has 40

stamps; 40 men are employed. The San Justo Mining Company,

Parrott Building, San Francisco, owners. V. W. Miller of Angels,
superintendent.

Greek Mine. — Near the road between El Dorado and Railroad Flat, 20
miles from San Andreas. It is developed by a shaft 170 feet deep, with
a drift 120 feet long at the 100-foot level. The vein cuts vertically
through mica schist, and has the remarkable accompaniment of two
dikes — the older a dark-green, hard diorite; the later, a light-colored)
finely grained dike of acid type. The latter is usually found in contact
with the vein, which is either banded or massive, showing in places
coarse gold. The general tenor of the ore, however, is low grade. It is
equipped with a steam hoist and a 5-stamp mill. Idle.— — Greek Min-
ing Company of San Andreas, owners. F. J. Solinsky of San Andreas,
agent.

Ritter Mine. — This is 1-| miles north of Mountain Ranch, or El Dorado.
It is opened by a tunnel 410 feet in length, driven on a small vein of
granular quartz having a peculiar schistose structure. The rock is
extremely hard and flinty. One shoot of ore developed by this tunnel
and a raise produced considerable high-grade specimen rock. The vein
strikes N. 30° W., and is intersected by a larger quartz vein, striking
north and south and dipping 65 degrees east. This vein is dislocated
by the smaller vein a distance of 40 feet. A small force was at work

in the spring of 1900. Rodesino Estate of Mountain Ranch, owners.

Bonded to S. Redmond of San Andreas.

Blue Jay and Yelloiv Hammer Mines. — These mines are 2^ miles east
of Mokelumne Hill, near the Calaveras River, and comprise 3100 feet
on a banded vein in Calaveras formation. The vein is from 2 to 6 feet
wide, cutting mica schist and slate. It is usually accompanied by a

small acid dike. The property is in the prospective stage. F.

Courtmarsh et al. of Mokelumne Hill, owners.

Esperanza Mine. — It is 2^ miles northeast of Mokelumne Hill. Devel-
oped by an inclined shaft 1000 feet deep. The property is equipped with
hoisting works, 30-stamp* mill, and chlorination plant of three furnaces;
motive power, water. Idle in the spring of 1900, but it was said that
the mine was about to resume operations. Esperanza Mining Com-
pany, 220 Sansome Street, San Francisco, owners. Prescott Ely of
Mokelumne Hill, superintendent.

Calaveras Mine. — It is 2-| miles north of Mokelumne Hill, near Big
Bar bridge. It was described in former reports as the Garner. The vein.

124 CALIFORNIA STATE MINING BUREAU.

which occurs in diorite, is opened through an adit tunnel. A vertical
shaft is being sunk from the surface, calculated to reach the vein at
a depth of 350 feet, and a winze is being sunk below the tunnel, 70 feet
north of this shaft. The vein strikes N. of E., dipping W. 57°. The
ore is crushed in a 10-stamp mill, situated on the opposite side of the
Mokelumne River, in Amador County, power being furnished by a tur-
bine wheel, using about 1200 inches of water. The mill runs during the
day only. At the mill an air-compressor furnishes power for drills used
in the mine on the other side of the river. There are 24 men employed.

Calaveras Gold Mining Company, owners. Peter Houghton of

Mokelumne Hill, superintendent.

North Star Drift Mine. — This is 2 miles south of Mokelumne Hill, on
the Old Woman's Gulch blue lead. The channel has been reached by
means of a cross-cut tunnel, in 1360 feet March, 1900. This tunnel
is 6^ X 10^ feet. Nine men are employed, there being as yet no machin-
ery. North Star Mining Companj^, owners. P. Schuman of Mokel-
umne Hill, superintendent.

Ellen Vannan Drift Mine. — This is half a mile below the North Star
Mine in Old Woman's Gulch, and on the same channel. It is opened

through an inclined shaft 195 feet deep. Six men are employed. W.

J. Jackson et al. of San Andreas, owners.

Green Mountain Mine (Hydraulic and Drift). — This mine was being
operated by hydraulic process with success during the spring of 1900,
under permit of the United States Debris Commission, employing 12
men during the day only. From a portion of this claim there have
been shipped, within the past two years, 12 tons of quartz crystals, for
which this mine has long been famous. These were placed with Tiffany
& Co. of New York, who estimated their value at about $18,000-
Several handsome and' absolutely perfect crystal spheres have been
cut from the crystals obtained in this mine, but the limit of the size of
a perfect sphere has thus far been about 5^ inches. A statement was
made to the writer by one of the owners, that Mr. Tiffany had said that
if a crystal could be obtained which would cut a sphere 7 inches in
diameter, which should prove to be absolutely faultless and Avithout a
flaw, such a sphere would have a valuation of $30,000. — —J. E. Burton
et al., owners. J. McSorley of Mokelumne Hill, superintendent.

Emery Hydraulic Mine. — Also known as the Rose Hill. One mile
from Mountain Ranch. This mine is situated on a branch of the Fort
Mountain channel. It was being operated in the spring of 1900 with
800 inches of water, and two monitors working twenty-four hours daily,
two pits having been opened. No work was in progress in the south
pit. The work in the north pit is being carried down stream, a long
tunnel having been cut for drainage. The water pressure at the upper

THE MOTHER LODE REGION — CALAVERAS COUNTY. 125

pit was 300 feet, at the lower pit 400 feet. The company owns 2^ miles
on the line of this channel. The bank has averaged thus far about 20
feet in height. From 2000 to 2500 yards are moved every twenty-four
hours, when a full head of water is available. The owners have spent
a large sum of money in perfecting their water-system, consisting of
reservoirs, ditches, pipe-lines, etc. In the mine 10 men are employed;

15 on other work. Emery Gold Mining Company of Mountain Ranch,

owners. Earle C. Emery of Mountain Ranch, superintendent.

San Domingo Hydraulic {Jupiter) Mine. — This property was being
worked in May, 1900, with two giants using 1500 inches of water under
150 feet head. The average of the season is estimated to be 1.25 yards
per day per inch of water employed. The bank is nearly 100 feet high ;
the gravel is loose, and disintegrates rapidly under the powerful streams
from the giants. The flume at this mine is 4 feet in width, 3000 feet
long, and set on a 4-inch grade. The company owns about 2 miles

on the channel. There are 8 men employed. The San Domingo Gold

Mining Company, Parrott Building, San Francisco, owners. A. B.
Thompson of Angels, superintendent.

French Hill Quartz Mine. — This is a prospect situated on the slope
of the famous French Hill, about half a mile east of Mokelumne Hill.
A cross-cut tunnel is being driven, which in March was in 400 feet.

There are 5 men employed. J. E. Burton et al., owners. T. E. Mc-

Sorley of Mokelumne Hill, superintendent.

Satellite Copper Mine. — This property is near Campo Seco. When
visited in the spring, the inclined shaft was down 250 feet, and sinking.
The hoisting is being done by means of a gasoline engine, which appears
to give satisfaction. At this mine an 80-ton water-jacket furnace was
found in full blast, operated by Avhat is known as "partial pyritic
smelting," under the direction of E. J. Fowler, metallurgical engineer.
The furnace is of special design, constructed from plans made by Mr.
Fowler, in which 80 tons of material are treated daily, of which 50 tons
are ore, the remainder being flux. The charge consists of raw ore,
roasted ore, slag, limestone, and low-grade matte. In what proportion
these are charged was not learned. Mr. Fowler says that this method
of pyritic smelting is entirely feasible and successful on ores of this
class. The ores are chalcopyrite and pyrite. A little zinc is occasion-
ally seen. The ore contains but little silica, and quartz is brought from
the croppings of neighboring veins for flux. The Pennsylvania Man-
ufacturing Company of Campo Seco, owners. A. C. Harmon of Campo
Seco, superintendent,

Borger Copper Mine. — Near Campo Seco, and in the principal mineral-
ized zone of the district. A new shaft is being sunk on a promising
copper vein by Mr. C. Borger of Campo Seco. C. Borger, owner.

126 CALIFORNIA STATE MINING BUREAU.

Union and Keystone Copper Mines. — They are at Copperopolis, and
comprise a mile of locations on the copper belt. The mines were worked
extensively in former years, and produced a large amount of copper.
The principal workings are down to a depth of 800 feet. The mines
were closed down in 1893, and have since remained idle. They were
unwatered in March, 1900, but further than this active operations have

not been resumed. Union Copper Mining Company of Boston, Mass.,

owners. G. McM. Ross of Copperopolis, superintendent.

Lightner Mine. — This is 2 miles southeast of Copperopolis. It has a
strong iron gossan, which occurs in amphibolite schist. It is developed
by several adit tunnels and shallow shafts. The ore in the oxidized
zone is essentially gold-bearing, but being in the copper belt it is antici-
pated that in greater depth in the sulphide zone more or less copper

sulphide will be found. The mine has no machinery. Mr. Uren of

Alameda, Cal., owner. Mr. Lillian of Copperopolis, superintendent.

Royal Consolidated Gold Mine. — This is in Salt Spring Valley at
Hodson, 3 miles northwest of Copperopolis. Since the last report this
property has been extensively developed under new management. The
former operators worked a vein which dipped to the eastward at a low
angle, and confined themselves to the defined limits of the walls of that
vein. The quartz occurred in a series of large lenses in a dike of dia-
base. There are a number of nearly vertical transverse veins which
come down from the hanging-wall, intersecting the flat vein and passing
into the foot-wall, but, strange to say, no attention was given these
steeply inclined veins by the former management. The present man-
agement, however, undertook the exploration of the mine upon broader
lines, extending raises into the hanging-wall and sinking winzes into
the foot, with the result that large deposits of payable ore have been
developed both above and below the original Royal vein. In this mine
may be seen some of the largest stopes in the State. The mine is almost
absolutely dry, some of the stopes being dusty. Comparatively little
timber is employed in sustaining the ground, and in view of this fact
the lack of substantial pillars is the cause of comment among visitors.
Although this ground is among the best to "stand" of any I have seen
in this portion of the State, there is a limit to which this method of
mining may be carried with safety. A system of timbering and filling
must soon be inaugurated to avert disaster, as well ^ as to recover the
large ore reserves in sight in this mine. The shaft has been sunk to 900
feet from the collar, and the lateral development is extensive. The
property is equipped with a large steam hoist and a 40-stamp mill.

There are 100 men employed. Royal Consolidated Mines (Ltd.),

owner. J. C. Kemp van P]e of Hodson, manager.

THE MOTHER LODE REGION — CALAVERAS COUNTY. 127

Tlic Royal Mill. — The mill of 40 stamps is under the direction of J. S.
Shepard. In the old mill the 20 stamps weigh 850 pounds. In the
new addition to the mill 20 stamps weigh 1150 pounds each. The old
-tamps drop 6^ inches, and the new 5f inches, 104 times a minute. No. 1
punched tin screens (24-mesh) are used. The discharge is 4 inches
high, and is maintained closely to this by the use of ^-inch slats beneath
the chuck-block. The capacity of the mill averages 3^ tons per stamp
daily. The 20 heavy stamps of the mill crush about 14 tons more in
twent3'-four hours than the light ones. It may be interesting to state
that the capacity of this mill is determined by weighing every car of ore
that goes into the mill. There are 8 Wilfiey, 3 Johnson, and 1 Frue
concentrators. The pulp from the Wilfiey machines and also that from
the Frue is recleaned on two Wilfiey machines. The pulp ^rom the
Johnson concentrators is also sent over the Wilfiey machines. This is a
very unusual arrangement of concentrating tables, but is stated to work
very satisfactorily, producing clean concentrates. At present the sul-
phides are sent to Selbj^'s reduction works. The company has under
consideration the construction of an additional 60 stamps and a chlor-
ination works at the property.

128 CALIFORNIA STATE MINING BUREAU.

TUOLUMNE COUNTY.

Since the last report was issued by the Mining Bureau in 1896,
Tuohimne County has been the field of unusual activity in mining
operations. Encouraged by the success of the Rawhide, Golden Gate,
Black Oak, Jumper, and other important properties in this county,
many new enterprises were inaugurated, and during the years 1897, 1898,
1899, Tuolumne County was giving employment to a large number of
men; but, as has been the case elsewhere, some of these investments
have thus far proven unremunerative, and in a few instances the propo-
sitions have been abandoned permanently, though in other cases sus-
pended operations will doubtless be resumed. A light rainfall through
several successive seasons has caused a shortage of water-supply, which
has also seriously affected the mining industry in this county, more so,
apparently, than in the neighboring counties, for at this time mines
which have been steadily operating for years are shut down owing to
lack of water for power. As an offset to this unfortunate condition is
the fact that several of the mines which have been in process of develop-
ment are proving valuable properties, and will form welcome additions
to the list of active producing mines of the county. Notable among
these are the Ea,gle-Shawmut near Jacksonville, and the Densmore near
Columbia.

There is considerable activity in the districts of smaller mines on
the East Lode, and reports of good new properties in that region may
be anticipated. There still remains a large territory unexplored in
Tuolumne County, both on the Central Lode and on the East Belt.
Besides these there are mines of known merit in the Sierras which must ere
long attract the attention of capital. Passing southward from Calaveras
County into Tuolumne at Robinson's Ferry, the Central Lode is found
to continue in an almost unbroken line to the southern boundary of the
county and beyond into Mariposa. There is a slight break in its con-
tinuity near Tuttletown, and another break of about 1000 feet between
Whisky Hill and the Dutch Mine, and still another near the foot of
Priest's Hill on Moccasin Creek. There may be other interruptions in
its continuity, but the instances mentioned are the most noticeable. In
fact, the lode is practically continuous through this county; and, as
elsewhere, it is characterized by its massiveness and distinguished by
the persistent occurrence of massive quartz croppings and broad zones
of ankerite. Some of the most important mines on this lode are found,
not in this belt of ankerite and quartz, but in amphibolite schist on the

I

THE MOTHER LODE REGION — TUOLUMNE COUNTY. 129

hanging-wall side of the ankerite zone. The Jumper and Eagle mines
are notable examples. The East Lode in Tuolumne County occurs
in the grano-diorite and slates. An intermediate belt lies between
these two lodes, in which occur numerous pocket mines in greenstone,
slate, and limestone. Mines of this class are prominent in the vicinity
of Sonora and near Big Oak Flat.

Bown Mine. — This is the first mine in operation on the Central Lode
south of the Stanislaus River. It is half a mile from Robinson's Ferry
and 2^ miles northwest of Tuttletown. A shaft had been sunk (June
27th) to a depth of 630 feet at an angle of 64 degrees. The vein, which
was being developed, is 10 feet wide and lies underneath the ankerite
zone, the foot-wall being schist and serpentine. The vein has a sinuous
course and a banded structure, containing gold and auriferous pyrite.
The shaft is in the foot-wall, the vein being reached by cross-cuts from
the shaft at 200, 300, 400, and 600 foot levels. On the 400-foot level a
cross-cut has been extended 128 feet beyond the vein into the hanging-
wall. The property is equipped with steam hoist and a 20-stamp mill,

in which are 8 Union concentrators. There are 20 men employed.

Bown Mining Company of San Francisco, owner. W. J. Rule of Tuttle-
town, superintendent.

Jackass Hill. — Half a mile south of the Bown and east of the anker-
ite zone are the pocket mines of Jackass Hill, the most important of
which are the Karrington and Stenchfield. This property is worked by
several sets of leasers, who pay to the owner a royalty on all gold taken
out. The mines are reported to have been regular and large producers
for several years past. James Gillis of Sonora, owner.

Norwegian Mine. — It is 1 mile north of Tuttletown, overlooking the
canon of the Stanislaus.

Arbona Mine. — It is at Tuttletown, about ^ mile east of the ankerite
zone, in greenstone schist. The vein is from 3 to 10 feet wide, and is
developed by a shaft 540 feet deep, and sinking in June. A 200-foot
cross-cut tunnel intersects the shaft at 135 feet from the surface. Levels
are run at 100, 200, 300, and 400 feet. The ore consists of massive quartz
and pyrite. The mine is equipped with steam hoist and 10-stamp water-
power mill. There are 12 men employed. This mine was worked many
years ago by French people, who undertook to crush the rock in arras-
tras, but the quartz was found too hard to crush readily, and it had

remained idle for years when the present owners renewed operations.

Equitable Mining and Milling Company of Stockton, owners. W. E.
Brooks of Tuttletown, superintendent.

Rawhide Mine. — This property, 3 miles north of Jamestown, which for
several years past had attracted much attention by reason of its large
9 — MB

130 CALIFORNIA STATE MINING BUREAU.

and continued output, has within the past year been involved in litiga-
tion among the co-owners, and when visited very little information was
obtainable, probably owing to pending lawsuits. The property was in
operation, however. Usually about 100 men are employed. The surface
plant consists of a large hoist, a 40-stamp mill, and chlorination works.
Ballard, Martin & Nevills of San Francisco, owners.

Harvard ( Whisky Hill) Mines. — These are a half a mile west of James-
town, on the dolomitic zone, though the development of pay rock is
principally in a zone of amphibolite schist on the hanging- wall side of
the dolomite. There are two vertical shafts — one of 500 and one of 750
feet depth. These are connected by the 500-foot level from the south
shaft. The veins of pay rock consist of silicious amphibolite schist of
variable width up to 35 feet. The hanging- wall is amphibolite schist, hard
and firm, not gold-bearing, or only slightly so; the foot- wall is serpen-
tine. Hundreds of feet of levels have been driven in the ankerite zone,
but the values are chiefly in the zone of greenstone schist. On the 500-
foot level a cross-cut has been driven westward to the massive quartz
vein, probably the downward extension of the "bowlder" vein seen on
the surface. This cross-cut develops nothing of value. The property is
equipped with steam hoists at both shafts, and a 60-stamp mill which
is run by electricity. The mill has both Johnson and Dodd tables,
which effect a clean concentration of the sulphides. A series of cyanide
experiments is to be made, with a view to treating the sulphurets by
that method. The apron and sluice plates are 6 feet wide, divided by a
longitudinal strip down the center. The plates have a grade of 1:^ inches
to the foot. Thirty stamps were dropping at the time of ray visit.
There are two electric motors in the mill, each of 75 horse-power, each

motor being calculated to run 30 stamps. Harvard Gold Mining

Company, owners. J. P. Munger of Jamestown, superintendent.

Dutch Mine. — It is at Quartz Mountain, and has been in continuous
operation since 1893. The shaft has reached a depth of 1200 feet^
inclined at 58 degrees. There are ten levels in the mine. The develop-
ment is chiefly upon a zone of ankerite and mariposite 60 feet in
width, in which are many veins and lenses of quartz, bearing gold and
auriferous pyrite, though in greatly varying (|uantities. The pay zone
is usually found on or near the foot-wall side of the ankerite zone. The
foot-wall country consists of amphibolite schist, gabbro, tufaceous
slates, Mariposa clay slates, serpentine, and diabase. These are dis-
tributed somewhat irregularly. The hanging-wall side is principally
amphibolite schist, so far as could be observed. The pay shoots appear
to cross the ankerite zone from foot to hanging wall diagonally, the
intervening blocks of ground being much lower in grade. There is also
a noticeable series of slips in the mine, which show that the hanging-
wall side of the zone has in each case been forced upward. These slips

THE MOTHER LODE REGION — TUOLUMNE COUNTY. 181

like the schists dip easterly, but flatter than the schists. Northward on
the surface the ankerite extends for a distance of 1000 feet, then disap-
pears beneath the alluvial of the valley, but considerable rock-exposures
occur farther northward, and it is observed that the ankerite vein is not
continuous to Whisky Hill. There is an interval of not less than 1500
feet in which it cannot l)e found, though reappearing on the north side
of Woods Creek at the south end of the ridge known as Whisky Hill.
The Dutch Mine is equipped with a large steam hoist, the compressor
and mill of 20 stamps being run by electricity. There are 54 men
employed. A cyanide plant was being constructed early in July to

work the sulphides concentrated from the ores. Dutch Mining and

Milling Company of San Francisco, owners. Albert Trittenbach of
Quartz Mountain, superintendent.

The App and Heslep Mines. — These join the Dutch Mine, and are
situated on the northern end of Quartz Mountain. The vein consists of
a large mass of ankerite and quartz, with a black slate hanging and
diabase foot-wall. The main shaft is down 1000 feet, equipped with
Avater-power hoist. The mill has 20 stamps, and was in operation
during midsummer. There are 25 men employed. The App Con-
solidated Mining Company of San Francisco, owner.

Santa Ysabel Mines. — These occupy the southern end of Quartz Moun-
tain, comprising several claims of irregular shape and size. The
property was idle at the time of my visit, but it was reported that opera-
tions were to be resumed. Santa Ysabel Mining Company of Boston,

owner. E. A. Hardy of Quartz Mountain, in charge.

Jumper Group of Mines. — This property is situated on a low ridge half
a mile south of the village of Stent, and comprises the Golden Rule, New
Era, and Jumper mines. The Jumper is the principal mine, and is
being systematically worked. The Golden Rule has a large amount of
development, as. has also the New Era, the latter chiefly through the
medium, of levels extended into it from the Jumper. The general struc-
tural geology of the mine is not wholly unlike that of other mines in
the neighborhood. A cross-section taken in the Golden Rule in a long
cross-cut gives a good general idea of the geological structure. Through
the entire length of the hill the ankerite vein is prominent, with the
usual accompaniment of large quartz lenses; all of this rock is very low
grade in gold, however. The foot-wall country is diorite, separated from
the ankerite zone by a dike of serpentine of variable width (about 100
feet). The ankerite is divided into two zones by the intrusion of a large
dike of diorite similar to that forming the west country. East of the
ankerite zone is a succession of diorite and diabase dikes, which in part
are altered to amphibolite schist, and it is in this schist that the pay
zone is found. Easterly from this the formation is amphibolite schist,

132 CALIFORNIA STATE MINING BUREAU.

with dikes of granular diabase. This zone of schist is over 1000 feet
wide. In the Jumper Mine the gold occurs in a dike accompanying the
schistose zone, and in small veins and veinlets of quartz and calcite,
scattered irregularly, but always within certain definite zones, the outer
limits of which form the walls. The width of this zone varies from 4 or
5 to about 30 feet. In its earlier history an effort was made to work the
mine by selection of the better from the poorer portions, but owing to the
peculiar geological conditions obtaining .the present manager deemed
this method unsuited to the accomplishment of the best results, and the
method of selection was abandoned for that of stoping everything
between the walls. This might at first appear like an extravagant and
unnecessary course to pursue, but the results have proven eminently
satisfactory. The Jumper is one of the best worked and best managed
mines in the State. It is heavily and properly timbered. The walls
are hard — that is, there is no trouble from swelling ground. The main
shaft is down 1285 feet, and is equipped with air and electricity. Power
drills are employed. There are nine levels in the mine. The mill has
60 stamps, and has no concentrators, except one for experimental pur-
poses. There are 125 men employed. Jumper Gold Syndicate of

Glasgow, Scotland, owners. M. D. Kelly of Stent, superintendent.

The Eagle- Shawmut Mine. — This property is 1 mile north of Jackson-
ville, on the ankerite vein. Its distinguishing feature is the line of
massive quartz outcrop which forms great, wall-like masses along the
course of the vein. The hanging-wall country is amphibolite schist; the
foot-wall is slate. The principal developments of the mine consist of a
cross-cut tunnel driven 1100 feet through the foot-wall country to the
vein, and a shaft sunk at the tunnel level to a depth of 660 feet on the
vein. The ankerite zone contains veins or lenses of quartz, which carry
gold in paying quantities, besides which there is a broad zone of amphib-
olite schist on the hanging-wall side, in which is a gold-bearing shoot.
This rock contains 2 or 3 per cent of auriferous sulphide, and is one of
the most important developments thus far made in the mine. The super-
intendent, Mr. Charles E. Uren, has introduced what appears to be an
excellent system of stoping and filling in this mine. His plan is to put
a long raise to the surface from a point above the tunnel level. This
raise is driven at an angle of about 65 degrees above the horizon, the
slope being westerly. The formation and veins dip easterly at about 70
degrees. The walls are usually firm and hard. The incline above men-
tioned reaches the surface in an open cut, where the rock (being barren)
is suited for filling, and may be quarried cheaply. Stopes are started
and mining operations continued by cutting out the ground the full
width of the vein in the form of the letter "A", the base being longitudi-
nally of the vein and the angle at the apex being no less than 90 de-
grees, in order that rock may readily run on the slope. The floor of this

THE MOTHER LODE REGION — TUOLUMNE COUNTY. 133

stope is heavily stuUed and covered with lagging. The winze passes
directly through the ai)ex of this triangular stope, and waste is sent
down from the surface and the excavation filled. Stoping then progresses
in "slices" on alternate sides of the winze or raise. These slices are
from 15 to 20 feet in height, the pay rock passing down through mill-
holes cut through from the level below, the ore-chutes being carried up
by cribbing, keeping even with stoping operations, and the filling run in
first one side and then the other, until the block is worked out. The
levels below are worked in similar manner, the filling passing through
the stationary loading chutes (at the levels) and across the track into
the next winze beneath by use of an apron, which may be removed when
desired until again required. This method demands a minimum amount
of timbering and renders the mine safe as far a's caves are concerned.
It may be elaborated and extended from level to level and make avail-
able a large amount of ore at low cost of mining. In addition to the
ore deposits above referred to there is upon the surface a zone of amphib-
olite schist, which contains a finely disseminated gold. Experiments
have proven that this rock is amenable to the cyanide process. The mine
is equipped with a 40-stamp mill, in which are 17 concentrators — Frues
and Unions. The hoist is run by water power, and at present is situ-
ated near the inner end of the long tunnel. It is planned to raise the
shaft to the surface. The mine and premises are lighted by electricity.
Ore is sent out of the mine in long trains of cars hauled by a horse.
The cyanide plant has a capacity of 56 tons daily, a percolation plant
of 50 tons, and an agitation plant of 6 tons. A chlorination plant was

in course of construction in July. There are 100 men employed.

Charles E. Uren, superintendent.

Republican Mine. — It is ^ mile from Jacksonville, and comprises a
group of claims on the main lode, the principal ones being the Repub-
lican and Mammoth. The principal ore-shoot thus far developed is
from 2 to 8 feet in width. There remains much of the hanging-wall
country to explore, however, and satisfactory developments may be
expected in that direction. A tunnel has been run 750 feet through the
foot-wall country of the Mammoth claim to the vein, and a shaft sunk
in the tunnel 430 feet. The main shaft in the Republican is down 400
feet, with four levels opened. The company has a mill of 10 stamps at
the mouth of the Mammoth tunnel, though at present operating only
the Republican, the ore being hauled by wagons. The mill has 4
Frue vanners. A large air-compressor is situated at the mill, a pipe-
line running to the Republican shaft for the purpose of operating air
drills. The mill and compressor are run by water power, the company
owning a ditch and flume several miles in length; but owing to a
scarcity of water the past three years, this power has not been available
during the summer and fall months. The hoist at the Republican is

136 CALIFORNIA STATE MINING BUREAU.

secting the tunnel. This is at present the principal development and has
exposed an ore-shoot 200 feet long, 400 feet high, with an average thick-
ness of about 5 feet. In places it is 12 feet wide. This ore, it is stated,
will average $17 per ton. Some portions are heavily sulphuretted, and
run from $150 to $250 per ton. Of this, former owners shipped during
1899-1900 over $26,000 worth, net. In addition to the above described
development there are several other tunnels, shafts, winzes, etc. A main
tunnel was being driven 200 feet lower than the one above referred to,
which will deliver ore into the bin of the mill, which consists of two
batteries of 2 stamps each, with one Wilfley concentrating table. A
cyanide plant of 10 tons daily capacity also forms part of the equipment.
Though in a rugged caiion, the mine is favorably situated for economic
working, by means of adits, which will command over 600 feet of backs,
and then another tunnel may be driven still lower if desired. A ditch
owned by the Utica Company passes along the mountain side opposite
the mine, and will afford a cheap power; and, taken altogether, it is
one of the most favorably situated mines in the county. There were 20

men employed the latter part of June. -Hayward & Lane of San

Francisco, owners. L. R. Poundstone of Columbia, superintendent.

Confidence Mine. — It is 12 miles east of Sonora, at an altitude of about
4000 feet, in the granite area lying east of the Calaveras formation.
This is one of the most noted mines in the county, and has been worked
for years, producing, it is claimed, upward of $5,000,000. The vein
strikes N. 14° W., and dips east at 18° to 30°. The inclined shaft has
reached a depth of 810 feet, with a winze 200 feet below the 800-foot
level. The mine makes less than 60 gallons of water a minute. The
vein varies from a few inches to 15 feet in thickness. The granite is
much decayed from the surface to a depth of 300 feet, below which is
found a hard, normal grano-diorite. A light-colored dike rock, frequently
of pale-green color, due to chlorite, is usually an accomj^animent of the
vein. The ore is free milling, 1>ut contains a sulphide mineral difficult
to concentrate. Cyanide experiments are being made on this mineral
and also on the coarse sands which are separated from the tailings by
means of a form of spitzkasten. Seventy per cent of the material is
coarse sand, containing 95 cents per ton. The remaining material goes
to a Gates canvas plant. The total loss in tailings is $1.65 per ton.
The slimes below the canvas tables still contain $3 per ton. This is the
material to be experimented upon with the cyanide process, but, due to
its extreme fineness, the percolation method cannot be employed. The
property is equipped with a steam hoist and 30-stamp mill, of which
20 were dropping. A No. 24 punched tin screen is used, the discharge
being from 7 to 8 inches high. The capacity is 3 tons per stamp. There
are 3 concentrators with 6-foot belts, and 4 with 4-foot belts. Tailings
are run onto the canvas tables 9 hours before purifying. The experi-

THE MOTHER LODE REiJION — TUOLUMNE COUNTY. 137

ment of purifying was tried, but proved unsatisfactory. Confidence

Gold Mining Company of San Francisco, owners. N. Carmichael of
Confidence, superintendent.

Black Oak Mine. — It is 4 mile southwest of Soulsbyville, on the
East Lode, and includes the Black Oak, Carra, and Live Oak claims.
The mine was discovered about thirty years ago, and during its early
history gained little fame, but within the past five years it has come to
be recognized as one of the most important mines in the State. It
occurs in grano-diorite. The vein varies from 1 to 25 feet in width, and
has several branches coming in from the hanging-wall side. These
latter often contain heavy sulphide mineral of high grade. Thousands
of tons of this class of ore have been shipped to Selby's. The deepest
shaft is down 900 feet, at an angle approximately 65 degrees, the dip
being westerly and the strike north and south. The vein is intersected
at intervals by dikes of very hard dark-green diorite. These simply dis-
place the vein. One at the northern end is evidently in the plane of a
fault fissure, as the vein does not reappear on the north side of the dike,
as in previous instances farther southward. The throw is presumed to
be to the westward. If this assumption be correct, the Genevieve Mine,
lying about 4000 feet to the northward, may be the real extension of
the Black Oak vein. The mine is equipped with steam and water-power
hoist and a 30-stamp mill. A large slimes plant also forms an important
feature in the beneficiation of the ores. The ores are quartz, containing
iron, copper, lead, and zinc sulphides. Pyrrhotite, a magnetic iron sul-
phide of bronze color, is a prominent constituent of the ores, and is
characteristic of the granite veins on the East Lode. In the mill a
60-mesh screen is in use, the discharge being 6 inches high. The
30 stamps crush 35 tons daily, which is an unusually low duty for
stamps in California, but is probably due to the hardness of the rock
and the fineness of the screen. The management claims to be able to
make a higher saving by fine crushing. There are 10 concentrators in
the mill. The pulp from the batteries passes to the plates and thence
to the vanners. Forty per cent of the gold is saved in the batteries.
From the vanners all tailings go to the canvas plant, consisting of two
fioors 60 X 100 feet. From the canvas tables the pulp is elevated and
sent to the cyanide vats, where it is charged by means of a mechanical
device to insure an equal distribution of sands and slimes, and to pre-
vent as far as possible the formation of channels in the charge. The
pulp is treated by the percolation method for 80 hours, and then dis-
charged through the side doors into the creek. A 60-ton tank is sluiced
out in one hour with water under a 500-foot head. Sulphurets
obtained from the vanners and from canvas tables are worked in a sepa-
rate plant by agitation for a period of 36 hours, with an extraction of
9-4 per cent. The strength of cyanide solution employed on the tailings

138 ■ CALIFORNIA STATE MINING BUREAU.

is 0.25 per cent; that in the agitation process varies somewhat according

to the value of the ore. There are 50 men employed. Scott, Dow

& Co., owners. W. P. Scott of Soulsbyville, superintendent.

Eureka Con. (Dead Horse) Mine. — It is on the East Lode, at Carters.
The deepest shaft is down 1550 feet. The formation is mica schist of
the Calaveras formation. The vein is from 1 to 12 feet wide, and con-
sists of quartz and pyrite. The hoist and' mill are run b}'^ water when
available. The mill has 20 stamps of 900 pounds weight. There are
8 Frue concentrators in the mill. Formerly a canvas plant was opera-
ted in connection with the mill, but its use has been discontinued. A
cyanide plant on the property treats 2 tons of sulphides daily. This is
on concentrates from vanners. The screen in the battery is 38-mesh.
It is claimed that the extraction is about 90 per cent. There are 41
men employed. Alvinza Hay ward and Hobart Estate of San Fran-
cisco, owners. E. T. Kane of Carters, superintendent.

Providence {Gloster) Mine. — This property is 2 miles southeast of Car-
ters, in the cailon of the North Fork of Tuolumne River. Since the
last report this mine has come into prominence as a rich producer. It
was systematically opened during 1896-97, and equipped with hoist
and milling plant, to accommodate which expensive grading and road-
making were required, as the slope of the mountain is nearly 35 degrees.
A mile and a half of road, reaching from the bottom of the canon to
the mine, cost $5,000. The vein occurs in the black slates of the Cala-
veras formation, and will average 5 feet in width in the pay shoot. The
quartz contains 1^ per cent of sulphides. The shaft is down 850 feet,
with six levels. The mill has 10 stamps, but was not in operation in
.July last. Only development work was in progress in the mine. All
power is steam, water being very scarce in that locality. There are 12
men employed, though the full force is 30 when the mill is in opera-
tion. Tuolumne County Mining Company, owner. C. A. Holland

of Carters, superintendent.

Goldwin Mines. — This constitutes a group of three claims about a mile
westerly from the Providence Mine, and 10 miles southeast of Sonora.
The elevation is about 2000 feet. The strike is north and south, and
the dip east. Geologically, the property consists of a broad-fissured
zone with a system of parallel quartz veins of variable width, from 2 to
5 feet. The veins are often found accompanied by a light-colored dike.
The formation is a fine-grained mica schist. The quartz vein is usually
banded, and contains auriferous sulphides. A tunnel has been driven
850 feet on the vein and a shaft sunk 250 feet, in addition to which
there are several short tunnels and winzes. The property is equipped
with a substantial hoist driven by air, and a water-driven air-com-
pressor. The company has constructed a dam in the canon and built a

THE MOTHER LODE REGION — TUOLUMNE COUNTY, 139

flume to the mill site, thus having free water-power. It is reported that
this property has produced $150,000. It had been idle for many years
before coming into the hands of the present owners. There are 25 men

employed. Goldwin Con. Mines, owner. W. H. McClintock of Sonora,

superintendent.

Dreisam (Easton) Mine. — It is on the East Lode, at Arrastraville. The
vein is from 12 inches to 3 feet in width, and is in grano-diorite. A
shaft had been sunk to 300 feet in July, and still sinking. The hoist is
equipped with both steam and water power. The mill has two batteries
of 6 stamps each, and two Frue concentrators. The mill is to be enlarged.

There are 30 men employed. Dreisam Gold Mining Company of San

Francisco, owner. W. Morehead, superintendent.

Grizzly Mine. — It is 1 mile south of Carters, on the East Lode. The
vein is 10 feet in width, has a banded structure in Calaveras slate, with
the usual accompanying dike. The shaft is down 750 feet, with levels
at intervals of 100 feet. The mill has 20 stamps, with 8 Frue vanners-
Water furnishes power for both hoist and mill. From 16 to 20 men

were employed in July. Grizzly Mining Company of San Francisco?

owner. W. R. Hall of Carters, superintendent.

Big Oak Flat District. — Since the last report there has been much
activity in and near Big Oak Flat. A score or more prospects of greater
or less prominence have been incorporated and a large sum of money
expended in their equipment and development. As is usual in such
cases, some of these have proven unsatisfactory and have been aban-
doned, while others are still developing, with fair prospects.

Longfellow Mine. — It is at Big Oak Flat, and is generally considered
as being on the East Lode, though this section is really between the
Central and East Lodes. The geology of the mine as described by the
superintendent is as follows: There are two veins about 50 feet apart,
the foot- wall vein being 10 to 12 feet wide and the hanging-wall vein
4 to 5 feet wide. There are many stringers of quartz in the slaty zone
inclosed between these two veins. The formation is slate. A shaft had
been sunk to 450 feet in July last. The surface equipment consists of
a steam hoist and a 10-stamp mill, with Wilfley and Frue concentra-
tors. A 30-ton cyanide plant was in course of construction the latter
part of July, and the tailings are to be treated by that method. During
the dry season water for milling is pumped from the Mississippi shaft

sunk on a vein in the granite of Big Oak Flat. Longfellow Gold

Syndicate of Glasgow, owners. A. P. Dron of Big Oak Flat, superin-
tendent.

140 CALIFORNIA STATE MINING BUREAU.

Mack Mine. — This adjoins the Longfellow on the east, and is on the
same vein. The shaft is down 430 feet at 35 degrees. Four levels are
opened, and the prospect is stated to be encouraging. The mine had a
steam hoist but no mill in the latter part of July. There are 12 men

employed. Mack Con. Mining Company of San Francisco, owner.

C. L. Lang of Big Oak Flat, superintendent.

A Gold-Bearing Zone. — This is found about 1 mile west of Big Oak
Flat, and extends for more than 15,000 feet along the mountain side,
and presumably could be traced farther. The formation consists of a
succession of black slates and diabase tuff. A description of the Criss-
Cross claim will answer in a general way for all of the numerous claims
along this belt for a considerable distance in either direction from it.
In that property the formation consists of Calaveras slates, and reefs of
diabase tuff. The slates occur in zones, some of which are relatively
soft and contain disseminated iron sulphides. The remaining portion
of the slates is usually hard, and less highly mineralized. The slates
are also intruded by dikes of diabase and porphyry. There are devel-
oped in this mine four zones -of what are termed by the miners "mineral
or metallic slates. " These zones are separated from each other by dikes
of variable width, not exceeding 20 feet. The slates strike north 30*^
W., standing vertical. The entire formation is intersected by seams and
veins of quartz, which strike about N. 30*^ E., dipping southeasterly at
60° to 70°. Some of these quartz veins, small at the surface, widen to
24 inches or more within a depth of 50 feet, and carry disseminated
gold, proving that these are not exclusively pocket mines, as has been
supposed. These vertical veins of quartz occur at intervals of 8 to 10
feet, having approximately a parallel strike. A second series of quartz
veins is found lying nearly horizontal, cutting the slates, and intersect-
ing the vertical veins. These veins occur at distances of 4 to 6 feet
apart, dipping at a low angle to the westward, thus dividing the forma-
tion into rhomboidal blocks. Frequently at the intersection of these
highly-inclined and flat veins a slight dislocation may be noticed, indi-
cating that there has been some movement of the formation since these
veins were formed. The gold found in this property is, as far as known,
confined almost exclusively to the zones of " metallic '' slates. In that
portion of the property to the northward the steeply-inclined veins have
been found to carry coarse gold in considerable quantity ; in fact, to
such an extent that many thousands of dollars have been taken from
rather superficial development by pocket-hunters. To the southward,
however, the gold in "the veins has been found chiefly in the nearly
horizontal seams and veins, and these have all produced largely. The
cause of this difference in the occurrence of the gold has not yet been
ascertained, but the fact that such is the case is of interest. As a result
of the operations of the pocket-miners there has been accumulated in

THE MOTHER LODE REGION — TUOLUMNE COUNTY. 141

the different dumps hundreds of tons of material, which, to the pocket-
miner, is waste, but it has been found by repeated tests that all of these
dumps carry considerable value in gold. It is an established fact that
the slates on either side of vertical veins carry gold for a distance of
2 feet or more from the vein. This also seems to be the case with the
horizontal veins. It may be that the gold-bearing zones constitute a
milling proposition, and that not only the quartz veins, but the slates
as well, may be mined and milled as a whole. In this respect these
gold-bearing zones bear some resemblance to the Jumper Mine near
Stent, in this county, where it has been found that the most economical,
and withal the most successful method of operating is to mine all the
material between the walls of the zone and the milling of all such
material, there being practically no waste.

142 CALIFORNIA STATE MINING BUREAU.

MARIPOSA COUNTY.

Since the publication of the last report of the State Mineralogist, Mari-
posa County has taken on more active life. The Mariposa Grant, cover-
ing an area of about 70 square miles, which for many years had lain
idle, has become the property of the Mariposa Commercial and Mining
Company, which has undertaken the active exploration and development
of at least five of the most important mines on the Grant. They are
going about this in a business-like wa}'^, and the indications are that if
there is any actual merit in the mines on the Grant it will be ascertained
by the present operators. A hasty visit was made to this field of opera-
tion in the latter part of May last for the purpose of investigating what
had been done and what was expected of these mines in the future.

Mariposa Mine. — This property, worked many years ago, it is reputed
at one period with great success, but which had been idle for more than
thirty years, has been reopened, and an inclined shaft sunk which had
reached a depth 475 feet on May 15th. The shaft was carried down at
a uniform angle, but the vein passed out into the hanging-wall at about
400 feet from the surface. In cutting a station at 475 feet, the vein was
discovered in the hanging-wall. The walls are diorite-porphyrite, and
very hard. The vein has little or no gouge, but generally breaks free
from the walls. The center of the vein is usually massive, with a banded
structure near the walls, and in some portions the entire vein shows the
banded structure. It varies greatly in width, from a seam to 12 feet or
more. It strikes N. 70° W., with a variable dip to the southward, which
will average about 60 degrees. Several hundred feet west of the new
shaft a branch breaks into the foot-wall, striking N. 50° W. A shaft,
now caved and filled with water, is sunk at the point of divergence. It
is said that large amounts of gold were taken from this shaft in the form
of pockets by the early miners. A report of Dr. R. W. Raymond,
"Mineral Resources West of the Rocky Mountains," 1868, states that
the Mariposa Mine was closed at that time, for the reason that mining
operations were no longer profitable, though the rock contained nearly
$10 gold per ton. It has been ascertained by careful sampling of the
faces of the stopes abandoned years ago, that considerable bodies of rock
were left, which averaged over $7 per ton, where the vein was from 2 to
4 feet in width. During the past summer a long drift on the 400-foot
level has cut through a fine shoot of high-grade ore. The mine is
equipped with steam hoist and air-compressor, steam pumps, and other

THE MOTHER LODE UEGION — MARIPOSA COUNTY. 143

necessary machinery. There are 28 men employed. Mariposa Com-
mercial and Mining Company, owners, 320Sansome Street, San Francisco.
J. H. MacKenzie, Mount Bullion P. 0., general manager.

The Princeton Mine. — This property, situated at Princeton, 6 miles
northerly from Mariposa, has also been reopened after an idleness of
many years. A new inclined shaft has been sunk to a depth of 600 feet,
penetrating some little distance below the old workings, very little of
which are at present accessible. Near the bottom of the shaft, two fine-
grained, ash-colored dikes intersect the vein at an oblique angle. They
have not "thrown" the vein, simply passed through it. In the bottom
of the shaft, at the time of my visit, the vein was about 4 feet in width,
of beautiful banded quartz. The entire vein from the surface to the
600-foot level is inclosed in the typical clay slates of the Mariposa beds.
These slates differ very materially from the black tufaceous slates so
closely associated with the rich ore deposits of Amador County, and to
which more particular reference is made under the head of Amador
County.

At this writing, the latter part of May, nothing more can be said of
the Princeton Mine, and only the future development of the property
can determine its real merit. The mine has an authentic record exceed-
ing $3,000,000 to a depth of 600 feet. In the foot-wall country, lying
immediately west of the Princeton vein, there are many veins, both large
and small, of gold-bearing quartz, and this section it is the intention of
the company to prospect. The mine is equipped with steam hoisting
plant and machine shop, and a 10-stamp mill is being erected for the
purpose of testing ores from the several mines of the Grant. The central
office of the mines is located at Princeton. There are 30 men employed.
In the middle of September the shaft was down nearly 900 feet, the vein

averaging 3^ feet in width. J. H. MacKenzie, Mount Bullion P. 0.,

general manager.

The Josephine Mine. — This property is about 3 miles north of Bear
Valley, overlooking the Merced River, and immediately adjoins the
" Pine Tree," with which its name is usually associated. This is also
being operated by the Mariposa Commercial and Mining Company. The
manager has placed a hoist underground, and sunk a winze 200 feet
from the level of the "English" trail drift. A vigorous policy has been
inaugurated, and the vein will be developed as rapidly as possible. It
has been stated in numerous previous reports that the Josephine vein
splits off to the w^estward from the Pine Tree vein; that it continues upon
an independent course for a distance of nearly 15 miles, rejoining the
main lode near Piilon Blanco, 3 miles north of Coulterville. A careful
investigation has led to the conclusion that the Josephine vein returns
to and rejoins the Pine Tree vein within a distance of 3000 feet from

144 CALIFORNIA STATE MINING BUREAU.

where it diverges, at what is called the old Fremont shaft. The error
into which myself as well as others have been led was in presuming that
a line of disconnected croppings represented the Josephine vein, whereas
the croppings of the Josephine are absolutely continuous, and may be
traced from its point of divergence from the Pine Tree northward to
where it rejoins the Pine Tree vein. The hills are covered with a dense
growth of chaparral, manzanita, and greasewood, and the tracing of
this line of croppings was not an easy task, though not an impossible
one.

Both the Pine Tree and the Josephine veins are well exposed on the
level of the English trail drift, where, taking a cross-section at a point
437 feet below the croppings at the Fremont shaft, it is found that the
two veins converge on this level about 400 feet north of the point of
meeting on the croppings, showing that the line of convergence is not
vertical, i)ut inclined to the northward. A cross-cut at the point where
these veins converge on the English trail level, shows a body of quartz
40 feet in width, dipping uniformly to the eastward at an angle of 60
degrees. Along the drift which follows closely the Pine Tree vein, the
two great veins are separated by a mere seam no thicker than a knife-
blade. Northward, a mass of soft material composed of ankerite with
mariposite and quartz, separates the veins by a few feet. Still farther
northward the divergence is greater, and the Pine Tree vein shows a
gouge 1 inch thick on the hanging-wall side of the vein. A cross-cut
has been driven 25 feet eastward through a mass of crushed and highly
altered ankerite to a second gouge containing fragments of this rock-
mass. The gouge is from 1 to 2 inches thick, and is extremely tough,
but soft. The wall beyond is polished like a mirror, and was formerly
considered the hanging-wall of the vein. The material beyond the slip
is identical with that in the cross-cut (crushed ankerite altering to talc).
Serpentine occurs on the hanging-wall side of the vein on the surface
over 200 feet distant. The serpentine approaches nearer to the vein,
going northward, however, and in the tunnel driven near the Merced
River, about 1000 feet lower thaa the English trail drift, lies on the
hanging-wall side of a zone of material similar to that found in the cross-
cut above referred to (the altered ankerite). The ankerite, containing
mariposite, separates the Pine Tree and Josephine veins, and the material
grows broader as the veins diverge, but where they are 80 to 100 feet
apart and more, it does not fill the entire space between them — a gray
rock, amphibolite schist, lying next the ankerite.

The Josephine vein is distinguished everywhere along its course by
what may be termed its fragmental appearance. A banded structure is
frequently apparent, but mixtures of quartz and black slaty material

are the most persistent features. J. H. MacKenzie, Mount Bullion

P. 0., general manager.

CROPl'IXfJS OF THE MaEII'O.SA VeIX.

Croppings of the Louisa Mine, Covlterville, Mariposa County.

THE MOTHER LODE REGION — MARIPOSA COUNTY.

145

Pine Tree Mine. — This adjoins the Josephine, and is 3 miles north of
Bear Valley. One of the old tunnels driven by the former operators has
been cleaned out and retimbered, and a hoisting engine set up under-
ground about 600 feet from the mouth. Here a shaft has been sunk to
a depth of 300 feet below the level. Ventilation is secured by an upraise
through old workings above the hoist connecting with an upper tunnel.
The engine is operated by steam carried in from the boilers at the mouth
of the tunnel, the exhaust passing out through the raise. Owing to the
careful manner in which the steam pipes have been packed, there is
little condensation in the pipes, and the temperature at the station is

Fig. 35.

not uncomfortably warm. In sinking the shaft, a very interesting fault
was discovered about 300 feet from the platform, the character of which
is illustrated in the accompanying drawing (Fig. 35).

The indications are that the formation on the hanging-w^all side of the
fault has slipped downward, and that if sinking were continued on
that portion it would be found to cut out, though in what distance it is
impossible to say. The foot-wall portion, however, will extend down-
ward to indefinite depth. The shaft is being sunk through the heart of
the ore-shoot opened by the old company, it being the purpose to ascer-
tain as quickly as possible whether payable ore still remains in the
10 — MB

146 CALIFORNIA STATE MINING BUREAU.

mine, and if so, how much. The Pine Tree Mine is everywhere char-
acterized by its massiveness and its entire freedom from slaty inclusions
Iron pyrite occurs in the quartz, but is not abundant. The vein is
usually well defined by smooth walls, the foot-wall being always, as far
as observed, mariposite and ankerite. The hanging-wall side of the
quartz vein is a granulated mass of rock, containing many fragments
of what appear to be the ankerite. The real hanging-wall — normal
country rock, i. e., slate, diabase, or serpentine — has not been cut on the
English trail level. At the mouth of the old Pine Tree tunnel, now
caved and inaccessible, the serpentine is found close to the vein. South-
ward, up the hill, it is fully 200 feet away from the vein. In the river
tunnel the serpentine forms the hanging-wall of the vein — that is, it
lies on the hanging- wall side of the fragmental rock (crushed ankerite)
referred to as occurring on the hanging-wall side of the quartz on the
English trail level. In the river tunnel the Pine Tree vein splits up
and makes good-sized quartz veins in this fragmental material. In
places the quartz is confined to the foot- wall side, ranging in width from
4 to over 40 feet. In speaking of the vein the entire mass of ankerite
with the included quartz lenses is meant, though commercially only
that portion containing pay ore would be recognized as the vein.

Roma and Sierra Blanca (Quartz). — Three miles northeast of Col-
orado. A tunnel is being run 1400 feet to reach the vein. It had
reached a length of 915 feet September 1, 1900, and is being driven
through soft slate and schist at a cost of $4 per foot, including timber-
ing. All work is by hand, and the tunnel is 5 by 7 feet clear. The
timbers are obtained on the property. There are 12 men employed.
Lew Aubury of Mariposa, superintendent.

Mary Harrison. — This mine is on the southern portion of the Cook
Estate, 2 miles south of Coulterville. It is situated on the great
Dolomitic vein, the quartz occurring on the foot-wall side, being 4 to 6
feet wide. Both hanging and foot walls are diabase. Black clay
slates (Mariposa beds) and serpentine also occur in the immediate
vicinity of the vein. The deepest workings are down 900 feet, and still
sinking in July last. The ore-shoot is stoped from the 700-foot level
to the surface. The lower levels are extensive. A 40-stamp mill built
on the Potosi Mine, one of the group owned by this company, crushes
ore from the Mary Harrison Mine, with which it is connected by 4
miles of narrow-gauge railroad. No rock was being crushed at the time
of my visit. Hoisting is done by steam. There are 75 men employed.
In addition to the Mary Harrison, the company also owns the Louisa,.
Margaret, Potosi, Malvina, and numerous other claims on this large

estate, but the above described is the only one in operation. Merced

Gold Mining Company of Boston, owners. J. Mills of Coulterville^
manager.

THE MOTHER LODE REGION MARIPOSA COUNTY. 147

Bonanza Mine. — It is 5-1 miles south of Covilterville, near the Merced
River, on the Dolomitic vein. A cross-cut tunnel was in 280 feet in
July last, running to intersect the vein, which was said to be 50 feet in
width. The hanging-wall is slate and the foot-wall serpentine. A
20-stamp mill was in process of building, and a dam was being con-
structed in the Merced River for power. There are 25 men employed.
T. P. Brisland of Coulterville, manager.

Murphy Mine. — It is 3^ miles south of Coulterville, on the main
lode, having serpentine on the hanging-wall and slate on the foot, dif-
fering in this respect from the Mary Harrison, which it somewhat
resembles otherwise. A shaft had reached a depth of 145 feet the
middle of July, and two levels had been started. The property is
equipped with steam hoist, but has as yet no mill. There are 18 men

employed. The Guffy-Galey Gold Mining Company of Pittsburg,

Pa., owners. W. W. Elmer, superintendent.

Black Hill (Pumpkin) Mine. — It is 1 mile north of Coulterville, and
is in the prospective stage, a shaft having been sunk 60 feet, equipped
with horse-whim. Some rich ore has been found in recent development.
There are 5 men employed. John Boyd, owner. J. J. Dolan of Coul-
terville, superintendent.

Yosemite Hydraulic Mine. — It is 10 miles east of Groveland. The
company has built 11 miles of ditch flume and pipe-line the past year,
and made preparations to carry on hydraulic mining on an extensive
scale; the scarcity of water, however, has affected operations seriously.

When working full force 20 men are employed. W. J. Pender of

Groveland, superintendent.

148

CALIFORNIA STATE MINING BUREAU.

MADERA COUNTY.

As it was necessary to pass through Madera County in going into
Mariposa, a brief examination of two mines was made while in that
county. In the neighborhood of Grub Gulch prospecting is actively
being prosecuted, and also in the direction of Coarse Gold, but lack of
time precluded visiting that section the past season.

The Rex Mine. — This is a new property at Grub Gulch. It has been
opened within the past few months. An inclined shaft has been sunk

Ver-Tical Cross Section
Rex /^INEr

Grub Gulch. Madera County.

.^^j^b" Pi5placen?en+ of Older
^V^ by Later Vzlr?.

Fig. 36.

to a depth of 100 feet at an angle of 40 degrees to the eastward. At a
depth of 50 feet from the surface in this shaft, the Rex vein, which is
from a few inches to 14 inches in width and rich in free gold, was found
intersected by another vein, known as the Bullion, which dips to the
westward at an angle of 60 degrees, cutting the dip of the formation
nearly at right angles and displacing the Rex vein. The formation in

THE MOTHER LODE REGION — MADERA COUNTY.

149

which these veins occur is mica schist. That portion of the Rex vein in
the neighborhood of the shaft has been opened by a series of shallow
pits, and by means of these the direction of its strike can be traced along
the surface. After passing the Bullion vein, which in strike intersects
the Rex vein at a low angle, the Rex vein does not appear in line with
the croppings on the farther side of the Bullion vein. However, farther
to the northward is a vein which has the physical characteristics of the
Rex vein, and also carrying the same character of gold, and this vein
has been traced for more than 1000 feet from its intersection with the
Bullion vein, on the opposite side of which it can be no further recog-
nized. There is little doubt that these two disconnected veins are
identical, having been dislocated by the later Bullion vein. The accom-
panying sketches (Figs. 36 and 37) illustrate this occurrence. As

Pi^7<\N OF- R&x ^HP guLLiON Veins

a+-(5rub(^ulch\. iTIaclera Counry . Calif6rnia_

shov^"\2, pisplaceme.r\t"
^ later guLuioN

Fig. 37.

nearly as could be determined, the Bullion vein has displaced the Rex
vein about 70 feet, its downward extension lying in the foot-wall and

about that distance from the upper portion of the vein.- Charles M.

Ward and others of Grub Gulch, owners.

Ne Plus Ultra Copper Mine. — This property is 9 miles in a south-
westerly direction from Raymond, on the San Joaquin plains at Daulton,
It is" an old property which has been reopened since the publication of
the last report. Three shafts have been sunk on the mine, 125, 140, and
145 feet respectively. These are distributed along the vein for a dis-
tance of 1000 feet. The formation is chiastolite schist. The zone of
mineralization is 100 feet or more in width, in which there are several
shoots of ore having an approximate parallelism with many ramifying
branches. There are also dikes cutting the formation. The ore normally
is an iron-copper sulphide, but in the zone of semi-oxidation, between
the thoroughly oxidized gossan ores and the normal sulphide ores,
oxidation is taking place very rapidly. This oxidation results in giving

150 CALIFORNIA STATE MINING BUREAU.

out a large amount of heat, which occasions the mine workings to be
unusually hot. The ore taken from certain shoots in this mine, when
delivered on the dump, frequently takes fire within a few days by
spontaneous combustion, and on several occasions has set on fire the
cars in which the ore is transported to the smelter at Madera. A large
dump situated at the south shaft has been burning for some time, and
the ore now presents the appearance of an ore-pile which has been heap-
roasted in the usual manner. In this mine was observed one of the
very few underhanded stopes in the State. The method of working this
mine illustrates to a marked degree the unfortunate policy commented
upon in one of the first paragraphs of this bulletin, that of demanding
immediate returns from development of ore. There are 40 miners
employed in the mine, 15 on top, and 60 at the smelter, which is located

near the town of Madera. The smelter was not visited. California

Copper Company of 31 Nassau Street, New York, owner. Wm. Davidson
of Daulton, superintendent.

Several copper mines are being worked on Green Mountain about 10
miles northwest from Raymond, and there is one near White Rock,
about 15 miles southwest of Mariposa. These mines are shipping high-
grade, partly oxidized ores. They were not visited.

INDEX.

Page.

Age of Calaveras formation 7

Age of Gold Belt - 7

Age of Mariposa beds 8

Alteration in massive rocks 9

Alteration of basic rocks to steatite 14

Alteration of other massive rocks 13

Alterations of tuffs to schists and

slates 19

Altman Mine 98

Amador County 43

Amador Queen Xo. 1 -.. 44

Amador Queen No. 2 44

Amphibolite schists .- 8

Anderson Mine 44

Angel Mine 109

Ankerite, Alterations of, to talc... 21

Ankerite, Probable origin of 13

Ankerite vein, General features of 20

App and Heslep Mines, The 131

Arbona Mine 129

Argonaut-Kennedy vein, Geology of .. 56

Argonaut Mill, Experiments in 50

Argonaut Mine 50

Argonaut Slimes Plant 51

Azula Mine 86

Baliol Mine.- 75

Banded schists - 12

Bay State Mine 85

Bell signals... 40

Bell signals, California code of 40

Big Bonanza 121

Big Canon (see Oro Fino) 96

Black Hill (Pumpkin) Mine 147

Black Oak Mine, Water crevice in 25

Blue Jay and Yellow Hammer Mines. 123

Bolytho Mine 120

Bonanza Mine 147

Borger Copper Mine 125

Bovee Mine 119

Bown Mine 129

Buena Yista Mine 91

Bunker Hill Mine 80

Butte Mine 45

Calaveras County 100

Calaveras formation 7

Calaveras Mine 123

Page.

California bell signal code 40

California greenstone 8

Canvas plant, Zeila Mine 46

Carson Creek Mine (see San Justo) 123

Centennial Mine 82

Center Mine 91

Central Eureka Mine 64

Central Gold Belt 15

Central Lode 14

Chlorination works, Practice in Amador

County 81

Chlorination works, Utica Mine 118

Church Mine 92

Classification of rocks 16

Clay slates at Gwin Mine 19

Clay slates of Mariposa beds 15

Clay slates. Relation of to veins 15

Code of bell signals in California 40

Commodore Mine.. 103

Condensation in steam pipes 33

Connecting levels 28

Contact veins 15

Contents 2

Copper mines (Ranlett) 87

Cornish pumps compared with steam

pumps 33

Cost of milling dumps, Plymouth Con.

Mines 83

Cost of milling at Mahoney Mine 37

Cost of mining 35

Cost of mining at Kennedy Mine 39

Cost of mining at Mahoney Mine 36

Cost of mining and milling at Gwin

Mine ... 38

Cyanide plant, Utica Mine 119

Cyanide plant, Vandalia Mine 97

Daulton Copper Mine (see Ne Plus

Ultra) 149

Demarest Mine 107

Diamond drills, Use of 35

Dikes in granite 24

Dip of slate, schists, and veins 15

Dip of veins. Relation of, to mine

methods 31

Direct-acting steam pumps compared

with Cornish pumps 33

Divisions of the Gold Belt 14

152

INDEX.

Page.
Dolomite - - 13

Dolomitic vein 13-19

Dolomitic vein, General structural fea-
tures of — 13

Drainage of mines 32

Drake Properties (Ltd.) ---. 121

Dresiam (Easton) Mine 139

Dutch Mine 130

Dutton, Capt. C. E., quoted 12

Eagle-Sliawmut Mine, The 132

East Lode, The. - - 14, 21

El Dorado County 88

El Dorado County, Geology of. 88

Ellen Taylor Drift Mine 94

Ellen Vannan Drift Mine 124

Emerson shaft, Timbering 68

Emerson shaft of Wildman Mine G8

Emery Hydraulic Mine ..- - 124

Eruptive rocks at Logtown 89

Esperanza Mine 123

Eureka Slate Quarry 99

Experimental work. Keystone Mill 79

Fairbanks, H. W., Determinations by. 16

Fault in the Keystone Mine ..-. 77

Fault in the Princeton Mine 147

Fellowcraft (Bode, or Veritas) 105

Filling, Necessity of prompt 32

Filling of stopes 31

Filling, Where obtained 31

Ford Mine 107

Formation of mineral veins 22

Fortuna Mine - 98

Free American Mine 76

Fremont Mine -- 80

French Hill Quartz Mine 125

Gentle Annie Mine - 94

Geology of Argonaut-Kennedy vein ... 56

Geology of Gold Belt 7

Geology of Keystone Mine. 77

Geology of Pine Tree-Josephine Mine. 145

Geology of the Vandalia Mine 97

Geology of Wildman-Mahoney Mine.. 65

German Mine 90

German Mine, Peculiar intrusions in.. 90

Gold Cliff Mine .-- Ill

Gold-bearing zone, A 140

Gold Belt, Age of 7

Gold Belt, Central ..-- 15

Gold Belt, Geology of 7

Gold Belt, Divisions of 14

Golden Rule Mine (see Jumper) 131

Gold in granite 24

Gold in talc 86

Goldwin Mines 138

Gopher-Boulder Mine 98

Page.

Gover Mine (see Fremont) 80

Gowanus Mine 85

Granite areas 21

Granite, Dikes in 24

Granite, Gold in 24

Granite, Ores in 22

Granite, Veins in 22

Great Western Mine 120

Greek Mine 123

Green Momitain Mine (hydraulic and

drift) 124

Green Mountain Copper Mines 150

Greenstones of California similar to

Michigan.. 8

Griffith Mine 92

Grizzly Mine. 139

Gwin Mill, Practice at.. 103

Gwin Mine. 100

Gwin Mine, Clay slates in 19

Gwin Mine, Cost of mining and milling 38

Gwin Mine, Method of mining at 100

Gwin Mine, Method of timbering at ... 102

Harris Mine (see Big Bonanza) 121

Harvard (Whisky Hill) Mines. 130

Hay ward Hydraulic Mine 99

Hector or Mahoney Mill 71

Heslep Mine (see App) 131

Illinois Mine..- 107

Illustrations, List of 3

Intermediate levels 30

Ivanhoe Mine 84

Jackass Hill 129

Jack Hanlej' Mine 99

Josephine Mine, Geology of. 144

Josejjhine Mine, The 143

Jumper group of mines 131

Kennedy Mill... 54

Kennedy- Argonaut vein. Distribution

of ore-shoots in 53

Kennedy Mine 52

Kennedy Mine, Geology of vein in 56

Kennedy Mine, New vertical shaft 53

Kennedy Slimes Plant 55

Keystone Mill 79

Keystone Mine 77

Keystone Mine, Geological structure of 77

Kirkwood Mine 45

Kretcher Vein (see Bay State).. . 85

Larkin Mine 93

Last Cliance Mine 122

Last Chance Mine (El Dorado County). 91

Letter of Transmittal 4

Lightner Mill 109

INDEX.

153

Page.

Lightner Mine (at Angels) 109

Lightner Mine (at Copperopolis) 126

Lincoln Mine - 72

Lincoln Mine, Fault in 73

List of Illustrations 3

LodiMine (see Sheep Ranch) 104

Longfellow Mine..- 139

Mack Mine 140

Madeline Mine 91

Madera County 148

Mahoney Mill, Cost of milling at 37

Mahoney (or Hector) Mill, Practice in. 71

Mahoney Mine, Cost of mining at 36

Mahoney Mine, Geology of 65

Manila ropes in Ranlett Copper Mine. 87

Marguerite Mine 93

Mariposa beds. Position of - 8

Mariposa County - — 142

Mariposa Estate, Mining machinery on 40

Mariposa Mine 142

Mariposite - 13

Mary Harrison Mine 146

Massive rocks, Alteration of 9

Melones Consolidated Mine 121

Merced Gold Mining Company 146

Metamorphic rock and schist 8

Metamorphism of tuffs 12

Methods of mining 26

Mill practice at Utica-Stickle Mine 111

Mine bell signals 40

Mineral veins, Formation of. 22

Mining, Cost of 35

Mining, Cost of at Kennedy Mine 39

Mining, Cost of at Gwin Mine 38

Mining, Cost of by Wildman Co 36

Mining machinery. 39

Mining machinery on Mariposa Estate 40

Minnehaha Mine 95

Monitor Mine 98

Montauk Gold Mining Co. (see Zant-

graf) 99

Montezuma Mine 91

Mother Lode 14

Murphy Mine 147

Mutual Mine 74

Nashville Mine 91

Ne Plus Ultra Copper Mine..: 149

New York Mine (see Anderson Mine).. 44

Noonday Mine (copper)... 91

North Star Drift Mine 124

Norwegian Mine 129

Nugget Mine. 86

Oneida Mine 60

Oneida new shaft, Formations in 62

Ores in granite „ 22

11 — MB

Page.
Ore-shoots in Kennedy- Argonaut vein,

Distribution of 53

Origin of ankerite ].i

Oro Fino Mine 96

Pacific Mine, Placerville 13

Peerless Mine 45

Perlina Mine 120

Philadelphia Mine 84

Phcenix Reduction Works (chlorina-

tion) 81

Pine Tree Mine 145

Pine Tree Mine, Fault in 145.

Pine Tree Mine, Geology of 146

Pioneer Mine ^3

Pitted slates 15

Placerville Slate Quarry H

Plymouth Consolidated Mine, Milcng

dumps of 82

Pocahontas Mine, Amador County . „ 83

Pocahontas Mine, El Dorado'County.. 95

Pocket Mines (see Jackass Hill) 129

Potazuba _. 7(j

Princeton Mine, The . ^ i?,

Queen Mine

Ranlett Copper Mine _ S7

Rawhide Mine iJ9

Red Cloud Mine S5

Reduction Works, Phoenix 81

Relief Mine _ ... 121

Renshaw, J., on pumps . , 33

Revera Mine ._ ;,4

Rex Mine, The ,. 148

Rex Mine, Fault in the 148

Rhetta Mine 86,

Ribbon Rock and Tin Cup Mines 94

Ritter Mine 123

Rocks, Classification and descripl , of 16

Rocks, Eruptive, at Logtown.. 89

Roma and Sierra Blanca Mines.. 146

Royal Consolidated Gold Mine 126

Royal Mill, The 127

San Domingo Hydraulic (Jupiter/ Mine 125

San Justo (Carson Creek) Mine. .. 123

Satellite Copper Mine 125

Schists, Banded _ .. 12

Schists and metamorphic rocks 8

Selby Mine.. .43

Shaft, Arrangements to ventilate 34

Shenandoah Mine 84

Sheep Ranch Mine ^ 101

Sierra Blanca and Roma Mines llt»

Sierra Lode 15

Sills, Use of in tim-bering 3u

Slate Quarry, Eureka ... 99

^ J

154

INDEX.

Page.

"^ Slate Quarry, Placerville 94

South Eureka Mine --- 63

Sourh Keystone Con. Mine 77

South Spring Hill Mine 11

Spagnoli Mine 45

Spanish Dry Diggings -. 98

'Starlight Mine 95

Steam pipes, Condensation in 33

Steatite 14

fl Steam pumps compared with Cornish

^1 pumps - --- 33

St. Lawrence Mine - 120

Stopes, Superficial area of 30

Structural geology of the Gold Belt ... 7

Swelling ground - 27

Talc derived from alteration of ankerite 21

Talc mines 86

Timbering Emerson shaft, Wildman

Mine - - 68

Timbering in naines 30

Timbering in new shaft, Kennedy Mine 54

Tin Cup and Ribbon Rock Mines 94

Transition rocks 13

Treadwell & Guliana Mine 76

Tuffs altered to schists and slates. 19

TuUoch Mine 121

Tuolumne County 128

Umatilla Drift Mine 94

Union and Keystone Copper Mines 126

Union Mine - -. 92

Utah, Eruption on high plateau of 12

Pa

Utica Chlorination Works

Utica Cyanide Plant .__ '

Utica-Stickle Mill, Practice in.

Utica-Stickle Mine

Vandalia Mine

Vandalia Mine Cyanide Plant

Veins, Formation of

Veins, in granite _

Ventilation in shafts

Veritas Mine (Bode, or Fellowcraft) ..

Walls, Gangways in

Walls of veins, Mineralization of

Water in mines. Relation of to ore .

Waterjacket smelter at Ranlett 8

Whisky Hill Mines (see Harvard) IL'

White Rock Copper Mines

Wildman Co., Cost of mining by

Wildman Co., Cost-sheet excludes 1899-

1900 .- ••

Wildman Mill

Wildman-Mahoney Mine

Wildman Mine, New vertical shaft at. .
Williams, G. H., qvioted

Yosemite Hydraulic Mine

Zantgraf Mine .

Zeila Canvas Plant, The

Zeila Mill, Experimentsin

Zeila Mine ^

TIT
/ 23
C2S8

A--l-'--l Q^J

ENGlNEEgma

Storms, William H. , 1£59'
The Ilother Lode region
of California.

S acramento,
superintendent state
printing (l900)

PLEASE DO NOT REMOVE
CARDS OR SLIPS FROM THIS POCKET

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